It's a sobering thought, particularly when the metrics we depend on give us the confidence to embark on significant changes to our sites or marketing plans.
You have probably come across some of these inaccuracies before. You may be running a PPC campaign and find that the PPC engine reporting tool tells you that you have received X number of clicks, while your own web analytics or server logs tell you that you have received Y number of clicks.
Here are some other reasons why your metrics may be inaccurate:
- Metrics programs (not server logs) sometimes cookie people and count them when they revisit a page, but not via a Google ad.
- PPC programs sometimes put a time limit on counting visitors. In other words, the same computer clicking on the same ad in a matter of a few seconds may appear as one visit, not two. However, if the user revisits later in the day Google will count it as multiple users, where server logs may not.
- Server logs are sometimes not configured to capture all the information you need.
Recently we conducted a brief test that enabled us to track visits through both the tools provided by the PPC engines and an affiliate tracking program. The test was brief and the figures are small. However, this does serve to illustrate how different reporting tools can give you results which vary significantly.
Here are the results:
According to the My Affiliate Program tracking system, our number of visitors was over 20 percent higher than reported by the PPC engines.
What can you do to combat inaccuracies? Use and compare results from two quite separate reporting tools. Then identify discrepancies between the two. At least that way you will be aware of the areas where the figures might be unreliable, and protect yourself from making bad marketing decisions.
You'll find a full archive of our test results, and analysis within the MarketingExperiments.com Research Archives. The Marketing Experiments Journal publishes primary test results from work with our research partners once every two weeks. Subscription to the Journal is free and gives you full access to both our archives and teleconference calls. Subscribe here.
