Why not delete your cookies?
Are you aware that when using Internet Explorer and other browsers to surf the internet, your surfing history and habits can easily be viewed and tracked by third partys by your cookies.
Technology enables others to see and track all the sites you've visited! Deleting your cookies, downloaded internet files and images, prevents others from tracking your behavior.
There are plenty of reasons you might want to delete your cookies., and you should not trust all cookie removal software therefore you may have to delete cookies manually.
Cookies may contain credit card information and have passwords!
Deleting cookies can improve computer preformance especially on older machines
Almost 73.5% of all forturne 1000 companies admit they "record and review their employees' communications and activities on the job." This includes cookies.
Advertisers may track and record your movements and purchases!
Your computer may contain hidden or temporary Internet files left behind from surfing the Web. Frequently as you surf the Web, sites that you visit "push" information onto your computer without you knowing it and without your approval. These files, if left on your computer, may automatically spawn other objectionable Web sites or transmit personal information without your consent.
Things every Web site can find out about you
Thought your visit was anonymous? Think again. The Internet gives an image of anonymity, but dig a little deeper and you'll find it's a false front.
Almost all Internet sites, and certainly the bigger ones, collect information about their visitors. It's logged by the site server that sends Web pages to your computer, and the data is referred to as Web server logs or weblogs. You'll be surprised how much information your disloyal computer passes over to the site you're visiting. Nothing as serious as your name or email address, but probably much more than you'd expect. Here are the main items:
IP address
This is your "street address" for the Internet, it's a string of numbers that identify exactly where you are in the huge ever-changing mass of networks that make up the Internet. It has to be passed to the site so that it knows where to send the pages that you've requested.
The bad news is that your IP address is quite distinctive. It's easy to tell from the numbers which country you're connecting from and which Internet Service Provider you're using. The good news is that most ISPs use a rolling address system, so you get a different address each time you log on to the Internet (from a range held by your ISP). Though if you're using a computer on an office network it might have its own IP address that never changes.
Ultimately, you can be tracked down from your IP address. Even if it's a rolling address, your ISP keeps records of who is using any address at any given time. In the space of a few seconds they can link any address with a specific user. That's you. But naturally they're reluctant to do it, even for the police.
If you use a free ISP account that didn't need registration, the detail comes from your phone line. These accounts only work with "line recognition", which means the ISP receives your phone number when you log on. So however you access the Internet, you can be traced. The IP address collected by the site server for its records can be linked directly either to you or to your phone line.
Referring page
Many sites also collect referring page information. Your computer obviously knows where it's just come from, and the shameless electronic traitor freely passes this information on to the next site. "This is the site we arrived from," it says. Hey, who's in control here?
Browser and operating system
Your computer also tells its electronic friend at the other end what kind of browser you're using, including the version number, and what kind of operating system you have - Windows, Mac, Unix, whatever.
Screen details
Although not all computers do this, many also tell the site server what size screen you have (in pixels, not inches) and what kind of colour resolution you're using - 256, 16 bit, 24 bit. Is there no end to their treachery?
Pages viewed
And finally, without the assistance of your computer, the site server records everywhere you go on the site and how long you stay on each page.
So, these are just some of the reasons to delete your cookies.
Friday, April 27, 2007
Cookies
IN THEORY, COOKIE IS a darn-tootin' super idea for a publication. Take the kid-rearing tracts of years past, subtract the housewife stereotypes, add pinches of personality and pizzazz, and voilà: a mommy mag for the new millennium.
In execution, however, the mag plays much more like a cleverly veiled Lucky than anything boasting the tagline "all the best for your family" should. Cookie is no more about what's best for one's family than "The Empire Strikes Back" is about the feasibility of interplanetary travel. It's a mommy product bible, plain and simple, and the mag's attempts to camouflage this via cover lines like "Sneak In Whole Wheat: Get Your Kids to Go With the Grain" and "How to Temper the Tantrum" come across as wildly disingenuous. Basically, it's false advertising.
You can't fault the mag's creative team. On the design front, Cookie trumps just about every one of the 130-odd magazines I've reviewed in this space. Lisbeth Svarling's half-scrawled illustrations invest both the mom/kid horoscope page and "fight cub" tantrum-tempering piece with clever quirk, while the house-of-cards layout for the item on birth announcements breathes personality into a ho-hum topic. The photo spreads alternate between blissed-out beach shots and shimmery scenes from family get-togethers; not a single photo in the May/June issue feels posed.
Cookie also sweats the small stuff. For its editorial masthead, the mag arranges names in clock-like fashion around the big blue "O" of its logo. Never mind that the "O" more closely resembles a donut or a bagel than a cookie--such bursts of whimsy in unexpected places are Cookie's creative calling card.
No matter how sharp the layouts may look, however, they can't overcome the mag's slavish worship at the altar of commerce. There are watches with "sleek monochromatic faces" and "breezy" canvas bags and balms for "stressed skin" and makeup "tiny treats" and a whole lot of other crap that could just as easily have been plucked from Harper's Bazaar. That the mag won't rate a book or DVD lower than "not for all tastes, but worth a look" renders its reviews entirely moot. And apparently one of the six best ways to "preserve childhood ephemera with your own aesthetic" is to buy vintage T-shirts for your kids. Okay, then.
Most deceptive are the two pages of "{Cookie Cravings}," in which a bunch of products are showcased in typically sprightly layouts and accompanied by the usual moms-are-fab text. Only if you're paying attention--and gosh, that's why I'm here--do you notice the six-point, thin-fonted "Advertisement" in the way-upper-left-hand corner. At least the other advertorial pages highlight a company logo for all to see.
The irony is that Cookie does quite well for itself when it downplays the product whoring. The first-person piece on the decision to have a second child offers both wit and warmth, while the how-tos (on fostering solid grandparent-parent-child relationships and diminishing the frequency and intensity of toddler tantrums) convey smart tips in refreshingly to-the-point form.
But these moments are neutralized by Cookie's tendency to out-cute itself way too often. I'm willing to entertain any/all theories as to why a stat about the percentage of body weight gained by male marmosets during their partner's pregnancy belongs anywhere near this publication. A Q&A with a six-year-old "poet," a few lines from the Oregon state song... the ever-so-precious vibe gets grating really quick, and that's before the mag ranks "You Can't Always Get What You Want" among the "Ten Grown-Up Songs to Download For Your Kid." I understand the inclusion of "Octopus' Garden" and "Shiny Happy People" (though the latter makes me want to break things), but doesn't Mr. Jagger sing of a gal who "was practiced at the art of deception/I could tell by her blood-stained hands"? Whatever.
In the title's online media kit, Cookie's bakers blab that, philosophically, they believe that "being a good parent and maintaining your sense of style are not mutually exclusive." That may be true in reality, but in the magazine world, products and parents don't mix at least nowhere near as seamlessly as Cookie would have you believe. Until the publication decides to emphasize one or the other, it will remain an irritatingly schizophrenic read.
In execution, however, the mag plays much more like a cleverly veiled Lucky than anything boasting the tagline "all the best for your family" should. Cookie is no more about what's best for one's family than "The Empire Strikes Back" is about the feasibility of interplanetary travel. It's a mommy product bible, plain and simple, and the mag's attempts to camouflage this via cover lines like "Sneak In Whole Wheat: Get Your Kids to Go With the Grain" and "How to Temper the Tantrum" come across as wildly disingenuous. Basically, it's false advertising.
You can't fault the mag's creative team. On the design front, Cookie trumps just about every one of the 130-odd magazines I've reviewed in this space. Lisbeth Svarling's half-scrawled illustrations invest both the mom/kid horoscope page and "fight cub" tantrum-tempering piece with clever quirk, while the house-of-cards layout for the item on birth announcements breathes personality into a ho-hum topic. The photo spreads alternate between blissed-out beach shots and shimmery scenes from family get-togethers; not a single photo in the May/June issue feels posed.
Cookie also sweats the small stuff. For its editorial masthead, the mag arranges names in clock-like fashion around the big blue "O" of its logo. Never mind that the "O" more closely resembles a donut or a bagel than a cookie--such bursts of whimsy in unexpected places are Cookie's creative calling card.
No matter how sharp the layouts may look, however, they can't overcome the mag's slavish worship at the altar of commerce. There are watches with "sleek monochromatic faces" and "breezy" canvas bags and balms for "stressed skin" and makeup "tiny treats" and a whole lot of other crap that could just as easily have been plucked from Harper's Bazaar. That the mag won't rate a book or DVD lower than "not for all tastes, but worth a look" renders its reviews entirely moot. And apparently one of the six best ways to "preserve childhood ephemera with your own aesthetic" is to buy vintage T-shirts for your kids. Okay, then.
Most deceptive are the two pages of "{Cookie Cravings}," in which a bunch of products are showcased in typically sprightly layouts and accompanied by the usual moms-are-fab text. Only if you're paying attention--and gosh, that's why I'm here--do you notice the six-point, thin-fonted "Advertisement" in the way-upper-left-hand corner. At least the other advertorial pages highlight a company logo for all to see.
The irony is that Cookie does quite well for itself when it downplays the product whoring. The first-person piece on the decision to have a second child offers both wit and warmth, while the how-tos (on fostering solid grandparent-parent-child relationships and diminishing the frequency and intensity of toddler tantrums) convey smart tips in refreshingly to-the-point form.
But these moments are neutralized by Cookie's tendency to out-cute itself way too often. I'm willing to entertain any/all theories as to why a stat about the percentage of body weight gained by male marmosets during their partner's pregnancy belongs anywhere near this publication. A Q&A with a six-year-old "poet," a few lines from the Oregon state song... the ever-so-precious vibe gets grating really quick, and that's before the mag ranks "You Can't Always Get What You Want" among the "Ten Grown-Up Songs to Download For Your Kid." I understand the inclusion of "Octopus' Garden" and "Shiny Happy People" (though the latter makes me want to break things), but doesn't Mr. Jagger sing of a gal who "was practiced at the art of deception/I could tell by her blood-stained hands"? Whatever.
In the title's online media kit, Cookie's bakers blab that, philosophically, they believe that "being a good parent and maintaining your sense of style are not mutually exclusive." That may be true in reality, but in the magazine world, products and parents don't mix at least nowhere near as seamlessly as Cookie would have you believe. Until the publication decides to emphasize one or the other, it will remain an irritatingly schizophrenic read.
Wednesday, April 25, 2007
Web Audience Measurement by Cookie Counting Considerably Overestimated
comScore recently released a study that analyzes the validity of using cookie-based data to measure unique visitors and to guage the number of unique users that were served an ad by an ad server. The results indicate that Web site server logs that count unique cookies to measure unique visitors are likely to be exaggerating the size of the site's audience by a factor as high as 2.5, or an overstatement of 150 percent
A "cookie", a small text file inserted on a user's computer by a Web server, is often used by web servers to identify and authenticate, track, and maintain specific personal information. First-party cookies are those left on a computer by a Web site that has been visited, while third-party cookies are those left by a domain different than the site being visited.
The Study observed that:
31 percent of U.S. Internet users cleared their first-party cookies during the month.
Within this user segment, the study found an average of 4.7 different cookies for the site.
Among the 7 percent of computers with at least 4 cookie resets, the study found an average of 12.5 distinct first-party cookies per computer, accounting for 35 percent of all cookies observed in the analysis.
An average of 2.5 distinct first-party cookies were observed per computer for the site being examined.
Cookie Deletion Analysis (1st Party Cookies December 2006)
Number of Cookie Deletions/Resets
Percent of Computers
Avg. No. of Cookies per Computer
Percent of Cookies
Total Sample
100%
2.5
100%
1 or more
31%
4.7
58%
4 or more
7%
12.5
35%
Source: comScore, Inc., April 2007
Dr. Magid Abraham, President and CEO of comScore, concludes that "...with just 7 percent of computers accounting for 35 percent of all cookies, it's clear that a certain segment of Internet users clears its cookies very frequently. These ‘serial resetters' have the potential to wildly inflate a site's internal unique visitor tally, because just one set of ‘eyeballs' at the site may be counted as 10 or more unique visitors over the course of a month. The result is a highly inflated estimate of unique visitors for sites that rely on cookies to count their audience."
The analysis of third-party cookies revealed an average of 2.6 distinct cookies per computer in December, indicating a similar rate of overstatement as the first-party cookies.
Cookie Deletion Analysis (3rd Party Cookies December 2006)
Number of Cookie Deletions/Resets
Percent of Computers
Avg. No. of Cookies per Computer
Percent of Cookies
Total Sample
100%
2.6
100%
1 or more
27%
5.5
57%
4 or more
7%
14.2
38%
Source: comScore, Inc., April, 2007
Dr. Abraham also noted that "There is a common perception that third-party cookie deletion rates should be significantly higher than first-party cookie deletion rates. Because many PC users reset or delete their cookies using security protection programs, conventional wisdom dictates that people are more likely to selectively expunge third-party cookies, which are generally deemed more invasive, while maintaining their first-party cookies. But these findings suggest that selective cookie management is not prevalent... confirmed via a survey, with only 4 percent of Internet users indicating that they delete third-party but not first-party cookies."
Mohanbir Sawhney, McCormick Tribune Professor of Technology at the Kellogg School of Management, Northwestern University, commented "To measure audiences more accurately, it is important to link visits to unique individuals, not unique cookies. As privacy programs become more entrenched, cookie-based audience counts will get even more unreliable."
And Bill Cook, PhD, Senior Vice President for Research and Standards at the Advertising Research Foundation, adds "Reach and frequency metrics are the cornerstone of any media plan, and given the size of the discrepancies that can occur when counting cookies instead of people, the study underscores the importance of panel-based measurement. For the advertising community, an accurate understanding of reach and frequency within a given target audience is vital."
A "cookie", a small text file inserted on a user's computer by a Web server, is often used by web servers to identify and authenticate, track, and maintain specific personal information. First-party cookies are those left on a computer by a Web site that has been visited, while third-party cookies are those left by a domain different than the site being visited.
The Study observed that:
31 percent of U.S. Internet users cleared their first-party cookies during the month.
Within this user segment, the study found an average of 4.7 different cookies for the site.
Among the 7 percent of computers with at least 4 cookie resets, the study found an average of 12.5 distinct first-party cookies per computer, accounting for 35 percent of all cookies observed in the analysis.
An average of 2.5 distinct first-party cookies were observed per computer for the site being examined.
Cookie Deletion Analysis (1st Party Cookies December 2006)
Number of Cookie Deletions/Resets
Percent of Computers
Avg. No. of Cookies per Computer
Percent of Cookies
Total Sample
100%
2.5
100%
1 or more
31%
4.7
58%
4 or more
7%
12.5
35%
Source: comScore, Inc., April 2007
Dr. Magid Abraham, President and CEO of comScore, concludes that "...with just 7 percent of computers accounting for 35 percent of all cookies, it's clear that a certain segment of Internet users clears its cookies very frequently. These ‘serial resetters' have the potential to wildly inflate a site's internal unique visitor tally, because just one set of ‘eyeballs' at the site may be counted as 10 or more unique visitors over the course of a month. The result is a highly inflated estimate of unique visitors for sites that rely on cookies to count their audience."
The analysis of third-party cookies revealed an average of 2.6 distinct cookies per computer in December, indicating a similar rate of overstatement as the first-party cookies.
Cookie Deletion Analysis (3rd Party Cookies December 2006)
Number of Cookie Deletions/Resets
Percent of Computers
Avg. No. of Cookies per Computer
Percent of Cookies
Total Sample
100%
2.6
100%
1 or more
27%
5.5
57%
4 or more
7%
14.2
38%
Source: comScore, Inc., April, 2007
Dr. Abraham also noted that "There is a common perception that third-party cookie deletion rates should be significantly higher than first-party cookie deletion rates. Because many PC users reset or delete their cookies using security protection programs, conventional wisdom dictates that people are more likely to selectively expunge third-party cookies, which are generally deemed more invasive, while maintaining their first-party cookies. But these findings suggest that selective cookie management is not prevalent... confirmed via a survey, with only 4 percent of Internet users indicating that they delete third-party but not first-party cookies."
Mohanbir Sawhney, McCormick Tribune Professor of Technology at the Kellogg School of Management, Northwestern University, commented "To measure audiences more accurately, it is important to link visits to unique individuals, not unique cookies. As privacy programs become more entrenched, cookie-based audience counts will get even more unreliable."
And Bill Cook, PhD, Senior Vice President for Research and Standards at the Advertising Research Foundation, adds "Reach and frequency metrics are the cornerstone of any media plan, and given the size of the discrepancies that can occur when counting cookies instead of people, the study underscores the importance of panel-based measurement. For the advertising community, an accurate understanding of reach and frequency within a given target audience is vital."
comScore - The Great Debate
By now, nearly everyone in the web analytics community is abuzz over the recent release by comScore of a study on cookie deletion rates. comScore tracked a specific web site (advertised as a portal) and one 3rd Party Ad Serving network against a panel of 400,000 users. During the study, comScore measured how often the 1st Party cookies (issued by the portal) and the 3rd Party cookies (issued by an Ad Serving Network) were deleted and replaced. The results can fairly be described as startling in several respects.
First, comScore pegged 1st Party Cookie deletion rates during an average month at 31%. Second, comScore measured the number of cookies and found that there were a significant percentage (about 7%) of serial deleters – who ended up having more than 12 1st Party cookies from the Portal site during a month. Taken together, these numbers imply a dramatic error rate in the total unique visitors a site measured even during a month timeframe. Perhaps as, or even more, surprising, comScore tracked relatively little difference between 1st & 3rd Party cookie deletion. 3rd Party cookie deletion was higher (as almost everyone would have expected) but by a margin best described as small.
Some of the reaction to this is predictable. First, there is considerable skepticism about the findings themselves. Perhaps that’s justified. Lord knows there are plenty of flawed studies done, not least when the studying party has a strong self-interested stake in the outcome. In addition, the frequency of deletion coupled with the lack of disparity between 1st & 3rd Party cookies (where automated Spyware tools might provide an explanation) makes it hard for many people to understand. Are internet users really this consistent about deleting cookies when they have to do it manually? It does seem hard to believe. Keep in mind, as well, that we are talking cookie deletion – not rejection. So though 3rd Party cookies may share a similar lifespan to 1st Part cookies, they are considerably less likely to find their way onto a computer in the first place. And while the comScore study wasn’t especially clear about this, it doesn’t seem to have focused on cookie rejection at all.
There is a second common reaction summed up in the idea that this level of errors in reporting doesn’t much matter because analysts are concerned with trends not absolute numbers. Anil Batra of Zaaz, for instance, argues (here) that it would make no (or little) difference whether your site got 5k visitor or 3K visitors – the important thing is how your site is trending in response to your actions.
I’m afraid I can’t agree with this thinking. At first glance it’s not necessarily wrong-headed though I’d argue that in fact it’s important to know your actual audience size on the web - that real numbers do matter and not just trends. Imagine a conference organizer who wouldn’t tell sponsors how many visitors the conference draws – only that it is trending upwards. I doubt I’d sponsor a booth!
But this is really just the tip of the iceberg when it comes to analysis. After all, total visitors IS pretty far down on the list of statistics of interest to the analyst. Unfortunately, almost every single statistic that matters is going to be effected – and sometimes devastatingly – by this level of error in visitor tracking. Perhaps Zaaz doesn’t track "New" visitors to the site vs. returning ones. But I do. And when half of my "new" visitors are really heavy repeat visitors I can hardly hope that my analysis will be crisp. Then too, I’ve always believed that tracking repeat customers on a site is central to most eCommerce analysis. But with this level of error I’m misclassifying a big chunk of that behavior.
Or again, perhaps people aren’t worried about what tools or pages drove repeat visits or cross-session sales behaviors. But it seems important to me. For a portal site like the one tested by comScore, the bellwether analysis is content impact on engagement. I’d like to say that this analysis may still be possible with this level of error, but I’m not sure that it would be.
Not concerned about these little things? Well how about the fact that every one of your campaigns might be significantly mis-counted in terms of conversion? That seems pretty consequential.
In short, just because comScore isn’t focused on analytics but only on traffic reporting doesn’t mean the impact of their findings is limited to traffic. And the impact for analysis of this level of error in 1st Party cookies would be very bad indeed. That’s not an admission you’d probably expect to hear from a web analytics consultancy and I’m sorry if this constitutes breaking ranks, but our first commitment ought to be to the truth of the numbers.
On the other hand, I too have some caveats about the general applicability of these results to every site. First, it’s important to understand the difference between each statistic. The 31% 1st Party cookie rate is, in my view, probably the most damning statistic in the study. Why? Because unless the behavior is somehow related to the specific site in question, you’d expect it to hold up for every site. Or then again, maybe you wouldn’t. If we accept that this statistic represents manual deletion of cookies, then there are two alternatives. The first is that people simply erase all cookies. That’s certainly possible – maybe even likely since it’s so easy to do. But a user may also scan the cookies on the target system and since cookies are often quite identifiable it’s possible that some cookies are much more likely to be deleted than others. It may be that an Amazon or Charles Schwab cookie is much less likely to be deleted than an AOL one. That’s one of the reasons it would be very interesting to understand the qualitative part of the comScore study – namely, what deleters (especially "serial" deleters) were actually doing. In addition, I’d like to understand if this problem is especially severe for certain browser populations (Firefox). And are users simply setting their browser to delete all cookies every time they close? This might explain the behavior of deleters – they aren’t doing any manual work at all. It would also imply that for this segment even same day uniques are overstated.
As comScore positions the study, however, the most damning finding is probably the one about the potential traffic impact of serial cookie "deleters." And for their particular chosen site, the impact would indeed be considerable. But for many of our sites, this group would probably have much less of an impact. Why? Portal sites are unusual in attracting a very high volume of repeat visits. comScore reported an average of nearly 13 1st Party cookies during a month for the 7% of visitors with 4 or more cookies detected. For most of our client sites (that aren’t portals), the overwhelming majority of visitors will come much less often than this. And if only a very small percentage of visitors are multiple repeaters and only a small percentage (7%) of those are multiple deleters, then the impact is likely to be considerably less (in terms of percentage of total visitors) than for a portal site. It’s likely true that no set of sites has a higher percentage of frequent return visitors than a true portal.
I’ll be honest – I find the study worrisome. It’s not that I haven’t realized that cookie deletion is a significant issue or that the potential impact of frequent return visitors on visitor traffic eluded me. But every analyst knows there is a line between data that is fuzzy but useful and data that is too messy to analyze. And I’ll be honest as well in saying that we see many sites where the number of visitors flagged as "New" would be better explained by the comScore view of the world than by the one prevalent (including by us) in the web analytics world. Depending on how the comScore study shakes out, web analysts may be facing a significant rethinking of where we are relative to that "fuzzy" line for almost every kind of interesting analysis. For some types of sites, at least, this might drive our short-term tool kit back to the pathetic same session analysis we were stuck with in tools a couple of years back.
comScore has their own agenda, here, obviously. But to me, the issue is ultimately about much more than unique visitor counts. Perhaps Anil is right to discount the importance of that statistic. But in doing so, he’s surely missing the larger point. In my view, the basic analytic toolkit of visitor segmentation and cross-session tracking is at risk in light of these findings. What’s the point of visitor segmentation when your visitors are lost every couple of days? This is an issue the measurement community just can’t ignore. I remember when 3rd Party cookie rejection rates began to climb and the ostrich like mentality that insisted this wasn’t an issue. Till suddenly the vendors made it possible to use tagged 1st Party cookies and everyone began implementing first party cookies. Sadly, we may not have solved our problem.
Are there short-term solutions? Possibly. And they begin with getting a handle on the scope of the problem for your site and understanding how to protect your analysis from these problems. You can begin to get a handle on the issue for your site by examining the trends in "New" visitors – especially if you can measure from significant events like a measurement start, a new cookie, or major traffic spikes. You might also want to look at the percentage of New/Returning visitors by Browser type. If you have strong behavioral cues on your site (like Login), you can measure the degree to which these behaviors are used by "NEW" visitors. This percentage compared to total visitor usage is an excellent way to get a reasonable read on how much or little of a problem you have. Handling bias is trickier, but if you want to analyze, for example, whether types of tools or content drive repeat visits, then you’ll be wise to start with a universe of visitors that you can prove has remained cookie constant. How might you do this? By insuring that you segment for behavior in both the 1st and last month of your study. This will narrow your analysis, but insure that you’ve ruled out cookie issues.
In the end, every problem in data quality simple complicates the life of the analyst more and makes doing good analysis just that much harder. I don’t much care who wins the great traffic reporting war. But I care very much that web analytics have a mechanism for tracking with some degree reliability the over time behavior of visitors. Where there is a will, I’m confident our truly fine tool vendors will find a way. It may be incumbent on analysts to provide that will.
First, comScore pegged 1st Party Cookie deletion rates during an average month at 31%. Second, comScore measured the number of cookies and found that there were a significant percentage (about 7%) of serial deleters – who ended up having more than 12 1st Party cookies from the Portal site during a month. Taken together, these numbers imply a dramatic error rate in the total unique visitors a site measured even during a month timeframe. Perhaps as, or even more, surprising, comScore tracked relatively little difference between 1st & 3rd Party cookie deletion. 3rd Party cookie deletion was higher (as almost everyone would have expected) but by a margin best described as small.
Some of the reaction to this is predictable. First, there is considerable skepticism about the findings themselves. Perhaps that’s justified. Lord knows there are plenty of flawed studies done, not least when the studying party has a strong self-interested stake in the outcome. In addition, the frequency of deletion coupled with the lack of disparity between 1st & 3rd Party cookies (where automated Spyware tools might provide an explanation) makes it hard for many people to understand. Are internet users really this consistent about deleting cookies when they have to do it manually? It does seem hard to believe. Keep in mind, as well, that we are talking cookie deletion – not rejection. So though 3rd Party cookies may share a similar lifespan to 1st Part cookies, they are considerably less likely to find their way onto a computer in the first place. And while the comScore study wasn’t especially clear about this, it doesn’t seem to have focused on cookie rejection at all.
There is a second common reaction summed up in the idea that this level of errors in reporting doesn’t much matter because analysts are concerned with trends not absolute numbers. Anil Batra of Zaaz, for instance, argues (here) that it would make no (or little) difference whether your site got 5k visitor or 3K visitors – the important thing is how your site is trending in response to your actions.
I’m afraid I can’t agree with this thinking. At first glance it’s not necessarily wrong-headed though I’d argue that in fact it’s important to know your actual audience size on the web - that real numbers do matter and not just trends. Imagine a conference organizer who wouldn’t tell sponsors how many visitors the conference draws – only that it is trending upwards. I doubt I’d sponsor a booth!
But this is really just the tip of the iceberg when it comes to analysis. After all, total visitors IS pretty far down on the list of statistics of interest to the analyst. Unfortunately, almost every single statistic that matters is going to be effected – and sometimes devastatingly – by this level of error in visitor tracking. Perhaps Zaaz doesn’t track "New" visitors to the site vs. returning ones. But I do. And when half of my "new" visitors are really heavy repeat visitors I can hardly hope that my analysis will be crisp. Then too, I’ve always believed that tracking repeat customers on a site is central to most eCommerce analysis. But with this level of error I’m misclassifying a big chunk of that behavior.
Or again, perhaps people aren’t worried about what tools or pages drove repeat visits or cross-session sales behaviors. But it seems important to me. For a portal site like the one tested by comScore, the bellwether analysis is content impact on engagement. I’d like to say that this analysis may still be possible with this level of error, but I’m not sure that it would be.
Not concerned about these little things? Well how about the fact that every one of your campaigns might be significantly mis-counted in terms of conversion? That seems pretty consequential.
In short, just because comScore isn’t focused on analytics but only on traffic reporting doesn’t mean the impact of their findings is limited to traffic. And the impact for analysis of this level of error in 1st Party cookies would be very bad indeed. That’s not an admission you’d probably expect to hear from a web analytics consultancy and I’m sorry if this constitutes breaking ranks, but our first commitment ought to be to the truth of the numbers.
On the other hand, I too have some caveats about the general applicability of these results to every site. First, it’s important to understand the difference between each statistic. The 31% 1st Party cookie rate is, in my view, probably the most damning statistic in the study. Why? Because unless the behavior is somehow related to the specific site in question, you’d expect it to hold up for every site. Or then again, maybe you wouldn’t. If we accept that this statistic represents manual deletion of cookies, then there are two alternatives. The first is that people simply erase all cookies. That’s certainly possible – maybe even likely since it’s so easy to do. But a user may also scan the cookies on the target system and since cookies are often quite identifiable it’s possible that some cookies are much more likely to be deleted than others. It may be that an Amazon or Charles Schwab cookie is much less likely to be deleted than an AOL one. That’s one of the reasons it would be very interesting to understand the qualitative part of the comScore study – namely, what deleters (especially "serial" deleters) were actually doing. In addition, I’d like to understand if this problem is especially severe for certain browser populations (Firefox). And are users simply setting their browser to delete all cookies every time they close? This might explain the behavior of deleters – they aren’t doing any manual work at all. It would also imply that for this segment even same day uniques are overstated.
As comScore positions the study, however, the most damning finding is probably the one about the potential traffic impact of serial cookie "deleters." And for their particular chosen site, the impact would indeed be considerable. But for many of our sites, this group would probably have much less of an impact. Why? Portal sites are unusual in attracting a very high volume of repeat visits. comScore reported an average of nearly 13 1st Party cookies during a month for the 7% of visitors with 4 or more cookies detected. For most of our client sites (that aren’t portals), the overwhelming majority of visitors will come much less often than this. And if only a very small percentage of visitors are multiple repeaters and only a small percentage (7%) of those are multiple deleters, then the impact is likely to be considerably less (in terms of percentage of total visitors) than for a portal site. It’s likely true that no set of sites has a higher percentage of frequent return visitors than a true portal.
I’ll be honest – I find the study worrisome. It’s not that I haven’t realized that cookie deletion is a significant issue or that the potential impact of frequent return visitors on visitor traffic eluded me. But every analyst knows there is a line between data that is fuzzy but useful and data that is too messy to analyze. And I’ll be honest as well in saying that we see many sites where the number of visitors flagged as "New" would be better explained by the comScore view of the world than by the one prevalent (including by us) in the web analytics world. Depending on how the comScore study shakes out, web analysts may be facing a significant rethinking of where we are relative to that "fuzzy" line for almost every kind of interesting analysis. For some types of sites, at least, this might drive our short-term tool kit back to the pathetic same session analysis we were stuck with in tools a couple of years back.
comScore has their own agenda, here, obviously. But to me, the issue is ultimately about much more than unique visitor counts. Perhaps Anil is right to discount the importance of that statistic. But in doing so, he’s surely missing the larger point. In my view, the basic analytic toolkit of visitor segmentation and cross-session tracking is at risk in light of these findings. What’s the point of visitor segmentation when your visitors are lost every couple of days? This is an issue the measurement community just can’t ignore. I remember when 3rd Party cookie rejection rates began to climb and the ostrich like mentality that insisted this wasn’t an issue. Till suddenly the vendors made it possible to use tagged 1st Party cookies and everyone began implementing first party cookies. Sadly, we may not have solved our problem.
Are there short-term solutions? Possibly. And they begin with getting a handle on the scope of the problem for your site and understanding how to protect your analysis from these problems. You can begin to get a handle on the issue for your site by examining the trends in "New" visitors – especially if you can measure from significant events like a measurement start, a new cookie, or major traffic spikes. You might also want to look at the percentage of New/Returning visitors by Browser type. If you have strong behavioral cues on your site (like Login), you can measure the degree to which these behaviors are used by "NEW" visitors. This percentage compared to total visitor usage is an excellent way to get a reasonable read on how much or little of a problem you have. Handling bias is trickier, but if you want to analyze, for example, whether types of tools or content drive repeat visits, then you’ll be wise to start with a universe of visitors that you can prove has remained cookie constant. How might you do this? By insuring that you segment for behavior in both the 1st and last month of your study. This will narrow your analysis, but insure that you’ve ruled out cookie issues.
In the end, every problem in data quality simple complicates the life of the analyst more and makes doing good analysis just that much harder. I don’t much care who wins the great traffic reporting war. But I care very much that web analytics have a mechanism for tracking with some degree reliability the over time behavior of visitors. Where there is a will, I’m confident our truly fine tool vendors will find a way. It may be incumbent on analysts to provide that will.
Tuesday, April 24, 2007
Google wants cream, no cookies
GOOGLE is developing technology to try to appease critics who complain that its proposed acquisition of DoubleClick will lead to an erosion of online privacy, according to its chief executive Eric Schmidt.
Mr Schmidt also promised changes in the internet company's policies, saying Google would do whatever was necessary to quell a rising tide of complaints about lack of privacy that began with news of its planned $US3.1 billion ($3.7 billion) acquisition 10 days ago. "At the end of the day, people will be happy," Mr Schmidt said.
"That's because they have to be" or Google would lose both users and advertisers and its business would be at risk, he said.
Fears have been stoked by the potential for Google to build up a detailed picture of someone's behaviour by combining its records of web searches with the information from DoubleClick's "cookies", the software it places on users' machines to track sites they visit.
As the company that "serves", or delivers, the majority of banner ads seen by web users, DoubleClick's reach within its market is on a par with that of Google in the search business.
Mr Schmidt said Google was working on a way of handling cookies that would reduce concerns about the practice.
The technology has long been controversial, because many internet users do not realise their surfing habits are tracked.
Google has bowed to those concerns by not using cookies, though it has said it would change its policy after the DoubleClick acquisition.
"We have technology in that area that can make it much better," Mr Schmidt said, though he refused to give details of the technique before the company's discussions with regulators.
Besides privacy groups, the DoubleClick deal has also stirred unease among advertisers and other online media companies over the competitive advantage Google would gain from the vast amount of information it would have about its businesses.
Last week Mr Schmidt said that Google would consider arrangements to deal with those fears, such as keeping apart data about advertisers and media owners contained in Google and DoubleClick's systems.
While stoking fears about loss of privacy, greater use of personal data collected online could have benefits, from enhancing the personalisation of services to helping fight terrorism, he said.
"These are the conflicts of our age," he said.
"We're trying to find the right balance."
Mr Schmidt also promised changes in the internet company's policies, saying Google would do whatever was necessary to quell a rising tide of complaints about lack of privacy that began with news of its planned $US3.1 billion ($3.7 billion) acquisition 10 days ago. "At the end of the day, people will be happy," Mr Schmidt said.
"That's because they have to be" or Google would lose both users and advertisers and its business would be at risk, he said.
Fears have been stoked by the potential for Google to build up a detailed picture of someone's behaviour by combining its records of web searches with the information from DoubleClick's "cookies", the software it places on users' machines to track sites they visit.
As the company that "serves", or delivers, the majority of banner ads seen by web users, DoubleClick's reach within its market is on a par with that of Google in the search business.
Mr Schmidt said Google was working on a way of handling cookies that would reduce concerns about the practice.
The technology has long been controversial, because many internet users do not realise their surfing habits are tracked.
Google has bowed to those concerns by not using cookies, though it has said it would change its policy after the DoubleClick acquisition.
"We have technology in that area that can make it much better," Mr Schmidt said, though he refused to give details of the technique before the company's discussions with regulators.
Besides privacy groups, the DoubleClick deal has also stirred unease among advertisers and other online media companies over the competitive advantage Google would gain from the vast amount of information it would have about its businesses.
Last week Mr Schmidt said that Google would consider arrangements to deal with those fears, such as keeping apart data about advertisers and media owners contained in Google and DoubleClick's systems.
While stoking fears about loss of privacy, greater use of personal data collected online could have benefits, from enhancing the personalisation of services to helping fight terrorism, he said.
"These are the conflicts of our age," he said.
"We're trying to find the right balance."
Sunday, April 22, 2007
Cookie Crunching May Be Pumping Up Web Traffic
Internet cookies might not be as reliable an indicator of distinct Web site visitors as previously thought, according to a Monday report from Internet research company comScore.
A growing number of Internet users have taken to erasing their computer's cookies, which are unique identifiers inserted on a user's computer that reveal what Web sites someone has visited. While this might not seem like a catastrophic event, the deletion of these cookies could lead to inflated traffic reports for a particular Web site, according to the report.
Each time a user visits a Web site for the first time that Web site deposits a virtual checkmark, or cookie, onto the user's computer. That cookie prevents the Web site from cataloging repeat visits from the same user, thereby creating a more accurate count of new visitors to a particular online venue. If a user's cookies have been erased, however, that person's computer is registered as a new user when they visit a Web site, even if they have been there hundreds of times before.
ComScore evaluated a first-party Web site and a third party ad server that each receives more than 100 million hits each month.
Researchers found that 31 percent of U.S. Internet users erased their first-party cookies over the course of the month. As a result, Web sites could be inflating their web traffic by as much as 150 percent, according to comScore.
"These 'serial resetters' have the potential to wildly inflate a site's internal unique visitor tally, because just one set of 'eyeballs' at the site may be counted as 10 or more unique visitors over the course of a month," said Magid Abraham, president and chief executive of comScore, in a statement. "The result is a highly inflated estimate of unique visitors for sites that rely on cookies to count their audience."
Report authors found similar totals on the third-party ad server, with approximately 27 percent of users clearing their cookies at least once a month.
Many people think third-party cookies are deleted more often than first-party cookies because "many PC users reset or delete their cookies using security protection programs," Abraham said. "But these findings suggest that selective cookie management is not prevalent."
Comscore officials were not immediately available for comment.
Copyright 2007 by Ziff Davis Media, Distributed by United Press International
A growing number of Internet users have taken to erasing their computer's cookies, which are unique identifiers inserted on a user's computer that reveal what Web sites someone has visited. While this might not seem like a catastrophic event, the deletion of these cookies could lead to inflated traffic reports for a particular Web site, according to the report.
Each time a user visits a Web site for the first time that Web site deposits a virtual checkmark, or cookie, onto the user's computer. That cookie prevents the Web site from cataloging repeat visits from the same user, thereby creating a more accurate count of new visitors to a particular online venue. If a user's cookies have been erased, however, that person's computer is registered as a new user when they visit a Web site, even if they have been there hundreds of times before.
ComScore evaluated a first-party Web site and a third party ad server that each receives more than 100 million hits each month.
Researchers found that 31 percent of U.S. Internet users erased their first-party cookies over the course of the month. As a result, Web sites could be inflating their web traffic by as much as 150 percent, according to comScore.
"These 'serial resetters' have the potential to wildly inflate a site's internal unique visitor tally, because just one set of 'eyeballs' at the site may be counted as 10 or more unique visitors over the course of a month," said Magid Abraham, president and chief executive of comScore, in a statement. "The result is a highly inflated estimate of unique visitors for sites that rely on cookies to count their audience."
Report authors found similar totals on the third-party ad server, with approximately 27 percent of users clearing their cookies at least once a month.
Many people think third-party cookies are deleted more often than first-party cookies because "many PC users reset or delete their cookies using security protection programs," Abraham said. "But these findings suggest that selective cookie management is not prevalent."
Comscore officials were not immediately available for comment.
Copyright 2007 by Ziff Davis Media, Distributed by United Press International
Web counting tools 'need change'
The way web audiences are measured could be ripe for an overhaul, according to two reports out this week.
Measurements based on page-views and cookies (small text files which track net use) could be affected by changing user behaviour, the studies warn.
Net measurement firm comScore found cookies used to track user behaviour could be being over-counted.
A separate study argues that page-view measurements are outdated due to an explosion in audio and video content.
Serial resetters
There are several methods for measuring net audiences which provide critical data for advertisers.
Cookies - small text files inserted on a user's computers by a web server and unique to that computer's browser - can be used for authenticating, tracking and maintaining information on users.
In comScore's study, an analysis of 400,000 home PCs in the US found that a hardcore minority of web users are clearing their cookies from their computers on a regular basis.
This causes servers to deposit new cookies which in turn could lead to an over-estimate of unique users to a particular website.
It found that 7% of computers accounted for 35% of all cookies, which extrapolated could mean the size of a site's audience is being overstated by as much as 150%, said comScore.
"It is clear that a certain segment of internet users clears its cookies very frequently. These 'serial resetters' have the potential to wildly inflate a site's internal unique visitor tally, because just one set of 'eyeballs' at the site may be counted as 10 or more unique visitors over the course of a month," explained comScore president Dr Magid Abraham.
Perhaps unsurprisingly, comScore offers a very different approach to audience measurement - using the panel-based system favoured by the TV and radio industries which relies on using a representative sample of net users to gauge behaviour.
Measuring time
Its findings have led some advertisers and site operators to question current methodology.
"Cookie-based data are still a valuable resource, but this important study certainly underscores the fact that an accurate multi-dimensional picture of consumer behaviours must be compiled from multiple sources," said Jeff Marshall, senior vice president of Digital Managing Director at media agency Starcom USA.
A separate study by net measurement firm Nielsen/NetRatings questions how relevant it is to look at page views as a gauge of user behaviour in the light of new technologies and the increase in audio and video content.
The post Web 2.0 world is best represented by measuring time spent on particular websites, argues analyst Alex Burmaster.
Page-views metrics discriminate against sites with audio and video content and Nielsen/NetRatings argues that metrics based on the time spent on a website could be a more accurate method.
"As the technology that publishers use to deliver content to the user moves away from static, reloaded pages to more streamlined content such as online videos, the page view is becoming a less relevant gauge of where might be the best place to advertise online," said Mr Burmaster.
"Time spent is probably the best single indicator of user engagement although it can be a misleading metric for search and comparison sites that aim to help users find what they're looking for as quickly and efficiently as possible," he added..
While the biggest sites in the UK by page-view are Google and Facebook, measurement by the time spent on a site puts eBay and online game RuneScape at the top.
Britons spent almost 28 million hours on eBay during February, while visitors to RuneScape clocked up an average of 6 hours and 32 minutes per visit, according to Nielsen.
Measurements based on page-views and cookies (small text files which track net use) could be affected by changing user behaviour, the studies warn.
Net measurement firm comScore found cookies used to track user behaviour could be being over-counted.
A separate study argues that page-view measurements are outdated due to an explosion in audio and video content.
Serial resetters
There are several methods for measuring net audiences which provide critical data for advertisers.
Cookies - small text files inserted on a user's computers by a web server and unique to that computer's browser - can be used for authenticating, tracking and maintaining information on users.
In comScore's study, an analysis of 400,000 home PCs in the US found that a hardcore minority of web users are clearing their cookies from their computers on a regular basis.
This causes servers to deposit new cookies which in turn could lead to an over-estimate of unique users to a particular website.
It found that 7% of computers accounted for 35% of all cookies, which extrapolated could mean the size of a site's audience is being overstated by as much as 150%, said comScore.
"It is clear that a certain segment of internet users clears its cookies very frequently. These 'serial resetters' have the potential to wildly inflate a site's internal unique visitor tally, because just one set of 'eyeballs' at the site may be counted as 10 or more unique visitors over the course of a month," explained comScore president Dr Magid Abraham.
Perhaps unsurprisingly, comScore offers a very different approach to audience measurement - using the panel-based system favoured by the TV and radio industries which relies on using a representative sample of net users to gauge behaviour.
Measuring time
Its findings have led some advertisers and site operators to question current methodology.
"Cookie-based data are still a valuable resource, but this important study certainly underscores the fact that an accurate multi-dimensional picture of consumer behaviours must be compiled from multiple sources," said Jeff Marshall, senior vice president of Digital Managing Director at media agency Starcom USA.
A separate study by net measurement firm Nielsen/NetRatings questions how relevant it is to look at page views as a gauge of user behaviour in the light of new technologies and the increase in audio and video content.
The post Web 2.0 world is best represented by measuring time spent on particular websites, argues analyst Alex Burmaster.
Page-views metrics discriminate against sites with audio and video content and Nielsen/NetRatings argues that metrics based on the time spent on a website could be a more accurate method.
"As the technology that publishers use to deliver content to the user moves away from static, reloaded pages to more streamlined content such as online videos, the page view is becoming a less relevant gauge of where might be the best place to advertise online," said Mr Burmaster.
"Time spent is probably the best single indicator of user engagement although it can be a misleading metric for search and comparison sites that aim to help users find what they're looking for as quickly and efficiently as possible," he added..
While the biggest sites in the UK by page-view are Google and Facebook, measurement by the time spent on a site puts eBay and online game RuneScape at the top.
Britons spent almost 28 million hours on eBay during February, while visitors to RuneScape clocked up an average of 6 hours and 32 minutes per visit, according to Nielsen.
Cookies Wildly Overcount Web Visitors
By Max Kalehoff
"Why don't my server-log files match up with the comScore Media Metrix or Netratings stats?"
When I worked at Media Metrix in the late '90s, and later at comScore following its acquisition of Media Metrix, I heard that question (and plea) thousands of times. In fact, I was involved in numerous campaigns to educate clients and the broader Internet advertising industry on why panel-measurement and server-side traffic data differed so much.
The online media and advertising industry inherently wanted and needed third-party validation. But in the aggressive game of chest-beating over reach and audience, publishers couldn't easily ignore the discrepancies between panel-measurement ratings and their own server-log numbers. And with the latter consistently reporting higher, they still can't!
Of course, there are many reasons for the differences. For one, there is often confusion between tracking unique Web site users versus unique browsers. ISP and browser caching also prevent alignment between log-file and panel measurement. Then there is ambiguity because panel measurements tend to size specific locations and markets --such as by home, work or country -- versus including visitors from virtually anywhere in the universe.
But one of the biggest factors in log-file and panel-measurement discrepancy is Internet users' deletion of cookies, those little snippets of software that Web sites leave on your PC when you visit them, or which ad networks leave behind when serving you ads. They're so often trusted, especially when they reflect favorably, but so misunderstood.
While I no longer work at comScore, the company released this week an important analysis showing the validity of using cookie-based data to measure the number of unique visitors to individual Web sites, as well as the unique users that were served an ad by an ad server. The study -- an analysis of 400,000 home PCs included in comScore's U.S. sample during December 2006, not self-reported data -- examined both first-party and third-party cookies from one prominent Web site and a third-party ad-server network.
Key findings:
For the site analysis, comScore observed that 31 % of U.S. Internet users cleared their first-party cookies during the month. Within this user segment, the study found an average of 4.7 different cookies for the site. Among the 7% of computers with at least 4 cookie resets, comScore counted an average of 12.5 distinct first-party cookies per computer, accounting for 35 % of all cookies observed in the analysis.
Using the total comScore sample as a basis, an average of 2.5 distinct first-party cookies were observed per computer for the site being examined. This indicates that Web site server logs that count unique cookies to measure unique visitors are likely to be exaggerating the size of the site's audience by a factor as high as 2.5, or an overstatement of 150%.
ComScore's analysis of third-party cookies from the third-party ad server revealed an average of 2.6 distinct cookies per computer in December, indicating a similar rate of overstatement as the first-party cookies. For those computers where at least one cookie reset occurred, the number of third-party cookies observed was slightly higher than first-party cookies at 5.5.
While there is bound to be variance of cookie deletion among different users across different sites, these results are directionally compelling. Fred Wilson, a comScore investor and board member, commented on the analysis: "It's true that panel data is generally a lot lower than your own server logs. But that doesn't mean your server logs are right."
How are you reconciling panel data with your server logs?
"Why don't my server-log files match up with the comScore Media Metrix or Netratings stats?"
When I worked at Media Metrix in the late '90s, and later at comScore following its acquisition of Media Metrix, I heard that question (and plea) thousands of times. In fact, I was involved in numerous campaigns to educate clients and the broader Internet advertising industry on why panel-measurement and server-side traffic data differed so much.
The online media and advertising industry inherently wanted and needed third-party validation. But in the aggressive game of chest-beating over reach and audience, publishers couldn't easily ignore the discrepancies between panel-measurement ratings and their own server-log numbers. And with the latter consistently reporting higher, they still can't!
Of course, there are many reasons for the differences. For one, there is often confusion between tracking unique Web site users versus unique browsers. ISP and browser caching also prevent alignment between log-file and panel measurement. Then there is ambiguity because panel measurements tend to size specific locations and markets --such as by home, work or country -- versus including visitors from virtually anywhere in the universe.
But one of the biggest factors in log-file and panel-measurement discrepancy is Internet users' deletion of cookies, those little snippets of software that Web sites leave on your PC when you visit them, or which ad networks leave behind when serving you ads. They're so often trusted, especially when they reflect favorably, but so misunderstood.
While I no longer work at comScore, the company released this week an important analysis showing the validity of using cookie-based data to measure the number of unique visitors to individual Web sites, as well as the unique users that were served an ad by an ad server. The study -- an analysis of 400,000 home PCs included in comScore's U.S. sample during December 2006, not self-reported data -- examined both first-party and third-party cookies from one prominent Web site and a third-party ad-server network.
Key findings:
For the site analysis, comScore observed that 31 % of U.S. Internet users cleared their first-party cookies during the month. Within this user segment, the study found an average of 4.7 different cookies for the site. Among the 7% of computers with at least 4 cookie resets, comScore counted an average of 12.5 distinct first-party cookies per computer, accounting for 35 % of all cookies observed in the analysis.
Using the total comScore sample as a basis, an average of 2.5 distinct first-party cookies were observed per computer for the site being examined. This indicates that Web site server logs that count unique cookies to measure unique visitors are likely to be exaggerating the size of the site's audience by a factor as high as 2.5, or an overstatement of 150%.
ComScore's analysis of third-party cookies from the third-party ad server revealed an average of 2.6 distinct cookies per computer in December, indicating a similar rate of overstatement as the first-party cookies. For those computers where at least one cookie reset occurred, the number of third-party cookies observed was slightly higher than first-party cookies at 5.5.
While there is bound to be variance of cookie deletion among different users across different sites, these results are directionally compelling. Fred Wilson, a comScore investor and board member, commented on the analysis: "It's true that panel data is generally a lot lower than your own server logs. But that doesn't mean your server logs are right."
How are you reconciling panel data with your server logs?
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