Google Analytics 'User Count' not Matching Big Query 'User Count'

Question

Our Google Analytics 'User Count' is not matching our Big Query 'User Count.'

Am I calculating it correctly?

Typically, GA and BQ align very closely…albeit, not exactly.

Recently, User Counts in GA vs.BQ are incongruous.

• Our number of ‘Sessions per User' typically has a very normal
  distribution.
• In the last 4 weeks, 'Sessions per User' (in GA) has been several deviations from the norm.
• I cannot replicate this deviation when cross-checking data from the same time period in BQ

The difference lies in the User Counts.

What I'm hoping someone can answer is:

Am I at least using the correct SQL syntax to get to the answer in BQ?

This is the query I’m running in BQ:

SELECT

WEEK(Week) AS Week, 
Week AS Date_Week,
Total_Sessions,
Total_Users,
Total_Pageviews,
( Total_Time_on_Site / Total_Sessions ) AS Avg_Session_Duration,
( Total_Sessions / Total_Users ) AS Sessions_Per_User,
( Total_Pageviews / Total_Sessions ) AS Pageviews_Per_Session

FROM

( 

    SELECT

    FORMAT_UTC_USEC(UTC_USEC_TO_WEEK (date,1)) AS Week,
    COUNT(DISTINCT CONCAT(STRING(fullVisitorId), STRING(VisitID)), 1000000) AS Total_Sessions,
    COUNT (DISTINCT(fullVisitorId), 1000000) AS Total_Users,
    SUM(totals.pageviews) As Total_Pageviews,
    SUM(totals.timeOnSite) AS Total_Time_on_Site,


    FROM

          (
            TABLE_DATE_RANGE([zzzzzzzzz.ga_sessions_], 
                           TIMESTAMP('2015-02-09'),
                           TIMESTAMP('2015-04-12'))
          )                

     GROUP BY Week

  )


GROUP BY Week, Date_Week, Total_Sessions, Total_Users, Total_Pageviews,     Avg_Session_Duration, Sessions_Per_User, Pageviews_Per_Session
ORDER BY Week ASC

We have well under 1,000,000 users/sessions/etc a week.

Throwing that 1,000,000 into the Count Distinct clause should be preventing any sampling on BQ’s part.

Am I doing this correctly?

If so, any suggestion on how/why GA would be reporting differently is welcome.

Cheers.

*(Statistically) significant discrepancies begin in Week 11

Answer 1

Update:

We have Premium Analytics, as @Pentium10 suggested. So, I reached out to their paid support.

Now when I pull the exact same data from GA, I get this:

Looks to me like GA has now fixed the issue.

Without actually admitting there ever was one.

::shrug::

Answer 2

I have this problem before. The way I fixed it was by using COUNT(DISTINCT FULLVISITORID) for total_users.

Answer 3

In standard SQL use COUNT(DISTINCT fullVisitorId) Google Analytics shows an approximation for users, Big Query is exact. You can test this with unsampled reports in Google Analytics - numbers will match.

Also: GA uses all available data to count users, even where totals.visits is NULL! In contrast GA counts sessions only where totals.visits = 1!