Unique visitors to page dimension less than unique visitors to eVar saving page name

[philipk92120636]

Hi everyone!

The screenshot below shows the volume of unique visitors for eVar1 and the page dimension for the same page name.

We have one s.t() call on the page sending the page name to both s.pageName and eVar1. There are a couple of click events on the page, but these fire s.tl() calls so should not inflate the metrics like visits, unique visitors, page views etc. for eVar1.

As you can see, eVar1 unique visitors are generally much higher than unique visitors to the page dimension, until a point in early February when they match up (which should happen anyway).

We only started seeing this mismatch when we migrated to Launch so when things aligned again in February it was a pleasant surprise.

This appears to be a blip because since the last week of February, the unique visitors for the eVar are outstripping the unique visitors for the page once again.

I have to stress, there have been no configuration changes in Launch affecting the page in question. No new events, no changes to existing rules etc. Nothing. There have obviously been changes to our overall Launch configuration (i.e. rules modified or added to other parts of the site), and dev releases to our site, but nothing that would directly affect the Launch code or have an impact on how Analytics itself processes s.t() or s.tl() calls and calculates metrics.

This issue does not affect all pages on our site, and it seems like the only commonality between affected pages is that there are events triggered on the page itself.

I appreciate there is a lot to unpick here and more information will probably be required, but this has been bugging me for months.

Note that our site isn't accessible outside the UK if you want to do some QA.

[PratheepArunRaj · Accepted solution]

Dear Philip,

Just thinking about the real-world scenarios with proper implementation.

Page Views: This should ideally match because Page Name is mandatory to set Page Views.

Visits: How about this scenario? I landed the page (eVar1 and Page Name got 1 visit) and after 30 minutes, I have clicked on a button where event tracking is there. Now Visit will be incremented to eVar1 but not to Page Name because we cannot set page Name in s.tl() call.

Unique Visitors: How about this scenario? I landed the page on 28 Feb 2021 at 11:55 AM and clicked on the event on 01 March 2021 at 12:01 AM. Now Unique Visitor will be counted only to eVar1 but not to Page Name if we select March month alone.

In your case, the numbers are high with a consistent difference so not sure the above Unique Visitor scenario will be valid (Considering day numbers rather than the month as said in the example). I am thinking about the other real-world cases and whenever the Unique Visitors gap arises, mostly the problem would be in Safari because of Cookie Blocking. Give me some time, will get back to you.

Thanks, Arun.

[philipk92120636]

Thanks Arun. Page views do match up. The visits scenario shouldn't be an issue because the page has a 20 minute timeout, that navigates the customer to an error page as soon as the session expires.

[yuhuisg]

@philipk92120636 It might also be interesting to find out why the numbers aligned very well in February. That seems like the anomaly to me.

[H_L]

If try to compare "evar1 instances" and "pagename instances, or pageviews", will that match?

IMO, evar will be always higher than or equals to prop unless it's expiration set to "hit".

[philipk92120636]

The eVar instances are higher than the page views but this is simply because the eVar is being passed with an event in an s.tl() call which shouldn't have an effect on the visits or unique visitors metrics. Historically, the unique visitors has lined up perfectly for the page and eVar1 dimensions.

[jantzen_b]

Do any of the answers below answer your initial question? If so, can you select one of them as the correct answer? If none of the answers already provided answer your question, can you provide additional information to better help the community solve your question?

[philipk92120636]

Hi @jantzen_b, none of the answers so far address the issue. The key thing for me is that the visits and unique visitors metrics aren't instance or occurrence based metrics and are linked to s.t() calls so in my mind (and from our historical data), eVar1 with unique visitors should be more or less the same as the page dimension with the same metrics as they are explicitly passed at the same time. Regardless of eVar persistence and the use of s.tl() calls on the page for click events and so forth, if the eVar isn't being passed with an s.t() call it shouldn't iterate any of the page related metrics. I'm happy to provide more information, and I get that it's an issue that probably requires more knowledge of our implementation.

[jantzen_b]

Thanks for the additional context. Outside of the advice already offered, I'm not sure i have much to add. These types of questions are often very difficult if not impossible to answer due to how many different scenarios there would be to cover. The best advice we typically give to our Analytics customer is to analyze trends rather than deep inspection of the raw numbers. Due to the nature of the tracking technology and its dependancies on things like browser cookies, we cant and shouldn't assume that the data is perfect. This is why looking at trends and anomaly's is advised.