"Web Analytics reports have always been somewhat erratic. Different measurement methods show more visits or lower conversion rates than others, now we are closer to knowing how far to bend the lens to bring the picture into focus."

Jim Sterne, author of “Web Metrics: Measuring Web Site Success”

On November 20th 2003 RedEye released The RedEye Report, a study into the accuracy of IP and Cookie-based online management information. RedEye believes it is the first organisation in the world to compare IP and Cookie-based web metrics to a known set of results, allowing them to produce a free report that:

• Identifies the level of inaccuracy of IP-based and Cookie-based Web metrics for two different Web sites
• Explains why such errors occur
• Recommends what decisions they can be used for.

The study examined data from two of the UK’s busiest ecommerce websites, www.asda.com and www.williamhill.co.uk. Given that more than half of all page impressions on these sites are from logged-in users, they provided a robust sample to compare ip-based and cookie-based analysis against.

The results were staggering, for example an IP-based approach overestimated visitors by up to 7.6 times whilst a Cookie-based approach overestimated visitors by up to 2.3 times.

Percentage error in cumulative unique visitor figures over a 28 day period on one of the sites

The report goes on to detail RedEye-commissioned research that looked into what specific user behaviour was causing the errors. The NOP study of 1,000 British Internet Users (definition: spend at least one hour online in average week, representing 80% of the GB Internet base) revealed that whilst 71% of respondents were aware of cookies, only 18% of these did not know how to delete cookies, and 55% of them were deleting them on a monthly basis.

The report concludes that Cookie-based tracking, combined with appropriate weightings, is the only way to ensure data that is accurate enough to base strategic decisions upon.

However, no formula exists that can be easily applied to counteract the errors. What The RedEye Report did prove was that ‘a one size fits all’ approach is unlikely to be applicable. A significant difference in the weightings appropriate for the two sites studied means that further research that includes more sites in different sectors is required.

How Accurate Is Your Data?

In order to complete such a study, RedEye is appealing for suitable Web sites to take in further research. In exchange for allowing their figures to be used, RedEye will provide a detailed picture of how accurate their current management information is. Companies will get a much better idea of how many people really visit their web site, what percentage of visits are repeat and a set of weightings to use with their existing system going forward.

Best of all, RedEye is offering to complete a limited number of these data accuracy audits for FREE. To qualify for the audit, sites need to have a significant proportion of overall traffic generated by users that either logged-in or identify themselves positively in another way. RedEye will select sites based on the sector they are in, the volume of data they generate and the percentage of overall traffic that is likely to be from logged in users.

To apply for a free data accuracy audit or to get your free copy of The RedEye Report, click here.