Averages, estimates, trends, and context are some of the things to keep in mind as you navigate the data collected by Google Analytics to help you avoid being misled.
- Analytics can tell us what happened, but we have to figure out the “Why?” and sometimes additional tests are called for. Usability tests (where you watch people use your site, and ask them to think aloud as they do so) can be very illuminating. A great resource for getting started with usability testing is Rocket Surgery Made Easy: The Do-It-Yourself Guide to Finding and Fixing Usability Problems by Steve Krug.
- Averages can confuse the answers: are lots of people doing a little, or a few doing a lot? Before getting carried away by an exceptional number, check the details behind it to see what most visitors are doing.
- Be aware of context: take note of site changes, other campaigns, world events, etc.
Along the bottom of the line graph in Google Analytics, there is a space for “Annotations” which can be used to indicate changes that may impact the data (e.g. “On this date we launched our new site menu.”) Existing annotations appear as little chat bubbles.
- Trends can affect your data; take seasonal traffic and the day of the week into account. Your site may always see a spike on Sundays, for example, or decreased activity during August.
- Numbers are estimates: expired cookies and variances in user behavior can affect the totals. Try to get a large sample of data (over a longer period of time, perhaps) to help ensure that the relative relevance of your numbers is useful.