Google Analytics can sometimes be nasty, because some dimensions paired with segments don’t behave the way you might initially think. Thanks to Michael Janssens‘ and Maik Bruns’ comments on my question in the analysis group founded by Maik, I can sleep peacefully tonight and have become a bit wiser again.
The question came up today in the analytics course: How can it be that I have more new users than transactions when I’m in the segment “Has made a purchase”? The link to the report is here, my assumption was: If I have a segment of users who have made a purchase and use this segment in the “New vs. returning users” report, then I assume that in the area New visitors + Have made a purchase, I only see users who made a purchase on their first visit. However, we see here in this report 691 users, but only 376 transactions. If my expectation were correct, then these numbers should be equal. But they are not.
New users + Returning users > All users
We see other contradictions here as well, and for the sake of completeness, we will start with them. The number of new users is 53,263, that of recurring users is 14,578. However, we have a total of only 58,856 users, which is less than the sum of new and recurring users.
This discrepancy is easily explained: If a user comes for the first time within the reporting period, then they are a new user. If they come a second time within the reporting period, then they are also a returning user. They are therefore counted twice, once among the new users and once among the returning users. However, under “All Users” they are only counted once.
Let’s take a look at the column Transactions, we see that they are not counted multiple times. This makes sense, because they can only be defined as a transaction once.
Global pages distort the data
Maik also brought up the point that global pages display somewhat distorted data because Google Analytics restarts all sessions at midnight, so a new visitor who arrives at 23:55 and calls up a second page at 0:01 is also counted as a new visitor on this second day, just like on the first day. It’s the same user, but they are counted twice as a new user (see source here). But can that lead to us having so many more new users than transactions? Certainly, the Google Merchandising Store is globally and galactically active, but are things being bought around the clock to such an extent?
The solution: No Boolean AND
The solution (thanks, Michael!) lies in the fact that the segment “Made a Purchase” paired with “New Visitor” is not linked with an AND, i.e. we can have users here who have made a purchase at some point, but not necessarily on their first visit. This becomes clear when we compare our two segments with a segment that Michael has built:
Michael’s segment is designed to use the AND link:
We have sessions here where a user must be new and at the same time have at least one transaction. And we suddenly see that for 376 transactions, we have 373 users, i.e., there must have been users who had multiple transactions during their visit. In other words, the new visitors in our “Made a Purchase” segment did indeed make a purchase, but 691 minus 376 transactions were not made by these new visitors during their first visit, but rather at a later time. The connection between the report and the segment could be formulated as follows: Show me all users who had a transaction in any session and also made their first visit within the reporting period. It does not mean show me all users who have a transaction in their first session.
In the future, I will take a closer look at how to interpret the connection of a segment with a report. Because that was, as I said, something nasty.