The case of the disappearing users

Google continues its efforts to thwart me. In today's episode, we find that the number of unique users actually goes down when I increase the date range in Google Analytics.

238 users (formerly known as "unique visitors") in February + March:

254 users in March:

280 users in the last 12 days of March:

274 users in the last 11 days of March:

I believe the last two are correct. Before March 20, you keep increasing the date range and the count of users keeps decreasing. I wanted to see how far back this went (because eventually it would get to 0, right?), and I found that Sept. 12, 2013 - Mar. 31, 2014 shows 230 users, but if I keep going back (e..g., Jan. 1, 2009 - Mar. 31, 2014), it remains unchanged at 230 users. (Sept. 13, 2013 - Mar. 31, 2014 shows 231 users.) I can't figure out any significance of Sept. 13, 2013 or 230 users.

What is important, however, is that March 20 was the first day the site went live and started collecting analytics.

So the lesson here is, when collecting Google Analytics data from a range that includes when your site went live, the beginning of the range has to be that same go-live date.

If you're doing monthly reports and getting data back for the entire months of June, May, April, you have to be careful when you get March -- instead of getting the entire month of March from days 1 - 31, you have to get from March 20 - 31. If you extend the start of a range to include any dates from before a site went live and started tracking, then bogus data ensues. Yay Google!