Defaults to last 30 days. When you first log in to Google Analytics, the date will default to the last 30 days, starting yesterday.
You can see any day. You can change it to any time range that you like by either clicking on the desired date on the calendar (use the arrows to make unseen months visible) or by typing in a date in the box. Google Analytics accepts a wide variety of date formats (i.e. “3/3/2012″, “March 3, 2012″, “Mar 3, 2012″, etc.) but it won’t accept nonexistent dates or nonsensical date ranges — where the starting date is after the ending date.
You can compare two date ranges. Check the optional checkbox “Compare to past” and you can enter a second date range. Google Analytics will automagially provide percent change numbers for most of the metrics on any given page, making certain types of analysis irrationally easy. A couple tips:
- Take into account the length of time of the two comparable ranges. Comparing a 31 day month with a 28 day month, for example, would show an 11% change even if each day’s numbers were identical.
- Take into account variations in weekly traffic. For many content sites, comparing a Sunday to a Wednesday would almost always favor Wednesday regardless of other circumstances.
In general, when I’m comparing month over month traffic, I compare full weeks with full weeks. This means that I end up either omitting a few days in a month, bleeding over into another month, or overlapping. I choose that error over the error of comparing uneven days.