Recently, GA has introduced some new changes to its use of sampling. It appears that they have started using it in more cases. Reports that would never trigger sampling with the amount of visits involved are now using "
Take a look at this report using normal data for a site I monitor:
|Normal graphic (you can see Easter's impact) of Google (Paid/Organic) coming to a site|
Where did the traffic go?
Now look at the next two images which are the same report as above but with advanced segments applied:
Non-Paid Search Traffic: This should show the Google organic traffic the site received.
|Non Paid Search Traffic....I didn't think that I only bought PPC???|
|Data Dave is sad and confused. If Google the search engine is sending me this traffic, what is it if not PPC or Non-Paid|
What happened here?
OK, wait. What if I just looked at the same report showing all three segments at the same time. Perhaps, it will start to make sense (or not):
Nope. If anything, the results look even weirder and more distorted than when looking at the data individually. There sure seems to be a big time bug in the sampling trigging and calculation system of GA.
- With no segments applied, the site data looks normal....however:
- With segments applied, 1 month of relatively little data triggered sampling ("fast-access"). This never used to happen for relatvively little traffic in GA.
- In both cases of sampling, Google sent the site 0 visits during the month of April.
- Where GA showed visits, it was very incorrect (multiple stand.devs apart from the actual observed data)
- With sampling applied, in the first week of May, GA reports that Google PPC sent more way traffic than all of Google combined.
- Non-Paid alone surpassed All Visits traffic for a coupld of days as well.
Data integrity is the foundation for any analytics / decision support tool. We cannot improve our websites if we cannot rely and believe the data upon which we will be basing our decisions. Luckily, I am not alone in seeing this latest turn for the worse with GA and sampling.
Hopefully, they will fix it soon.