I'm using a session custom dimension to distinguish between two variants of my site. I'm setting this dimension to 'A' or 'B' for ALL visits before I track the first pageview.

My problem is that when I look at the number of pageviews in the report I see a much higher number than when I add my custom dimension as a secondary dimension and sum all of the pageviews.

for example, when I count all the pageviews for a certain day I get 100, but if I add a custom dimension as a secondary dimension I see that for 'A' I get 30 pageviews and for 'B' I get 30; overall 30 + 30 = 60. Where are the missing 40?

I assume that somehow the custom dimension is not properly set, but I can't tell why.

Any Ideas?

  • Are some sessions with Custom Dimension = (not set) ? Apr 21, 2015 at 4:35
  • Apparently yes, but for many of them I can't tell why. I see pageviews with unset custom dimension for pages where I explicitly set the custom dimension before the tracking of the pageview. The behaviour in inconsistent. For the same page I get some pageviews with the dimension set and some with the dimension unset.
    – davidrac
    Apr 21, 2015 at 6:09
  • Have you checked what the "hostname" dimension value is for the pages without custom dimension value? Another option: maybe some javascript error happens before the custom dimension value gets set.
    – Mehdi
    Apr 29, 2015 at 21:16

1 Answer 1


The pageview metric is incremented with every page load or reload, whereas the unique pageview metric is only incremented once per session. You could get a pageview count greater than 1, but your CD would only show 1 as it is session scoped. So you should be comparing your session-scoped CDs against unique pageviews instead.

  • The unique pageviews numbers behave in a similar way.
    – davidrac
    Apr 19, 2015 at 15:17
  • Are your uniques the same as pageviews? If so, then there's something else needing investigating. They shouldn't be the same, typically.
    – nyuen
    Apr 19, 2015 at 21:45
  • The uniques are not the same numbers as pageviews, but the behaviour is the same: the total amount of uniques is lower once I add the custom dimension
    – davidrac
    Apr 20, 2015 at 13:36

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