"Viewed before 'Goal XYZ' rate" is often 0% #19616

This issue is related to the new 4.11 feature described here:
https://github.com/matomo-org/matomo/issues/2030#issuecomment-928878139

Expected Behavior

The "Viewed before Goal XYZ rate" should "The ratio of conversions of Goal XYZ where this page was viewed prior to converting."

My understanding is that "was viewed prior to converting" means "was viewed in the visit prior to converting."
I hope this is right.

Current Behavior

I found a lot of page urls that were in the visit before the conversion and have now a"Viewed before a rate" of 0% and can't explain me this zero value.

See this screenshot please. This goal has 54 conversions.
The red marked page url has 22.64 conversions but 0% view prior rate.

Hi @utrautmann, thanks for reaching out.

You are correct, "was viewed prior to converting" does mean "was viewed in the visit prior to converting." :+1:

Some of the values used to calculate the 'viewed before' rate are generated during the archiving process. It's possible that conversions created prior to upgrading to version 4.11 do not have the archived values needed to correctly calculate the percentage.

If you choose a time period after you upgraded to 4.11, such as yesterday, do you still see any unexpected 0% 'viewed before rates'?

If not then I'd suggest invalidating and re-processing archives for the time period you want to view., This should make sure all the values needed to calculate the 'viewed before' rate are present, which should hopefully fix the problem.

Otherwise let us know and we can investigate further.

Hi @bx80 ,

the time that I choose in the screenshot was for 09/Aug/2022. I 've upgraded Matomo to 4.11 at 05/Aug/2022, so I think all report metrics were created after the upgrade.

I will look for another example with a more manageable amount of visits and goals - hopeful it helps you.

Hi @bx80 ,
here comes a simple example. I anonymized some informations.
We had 8 conversions yesterday for the goal "Klick auf Link zu uni-assist.de"

Let's take a deeper look to the first red marked URL. "Viewed before ... rate" is 0, but conversions are 0.5.
24 pageviews and 19 unique pageviews (this value we don't see here actually because of #19615 )

So I've extracted the visitor log for this first URL.
Please checked the attached PDF. The concrete URL is highlighted:
FireShot_Capture2022-08-10 - Webanalytik-Berichte - Matomo.pdf

We have 2 visits where the goal was achieved, but only one visit, where the page impression was prior the goal conversion.
8 conversions overall and 1 conversion with a page impression with this URL( view before... rate --> 1/8 = 0.13%)

Edit:
The visit with the page impression prior the goal conversion has also a page impression for this URL after the goal conversion.
Maybe here is the problem:

I hope my interpretation is correct, that something is wrong here.

Regards
Udo

Hi @utrautmann,

Thanks for the extra information, that's really helpful! :slightly_smiling_face:

It definitely looks like there is something wrong here, I'll investigate further :+1:

@justinvelluppillai I've added this to the current milestone since it's a potentially high impact issue with a new feature.

I would like to ask what the status is here? The problem is still there and shows incorrect values.

Hi @utrautmann, thanks for your patience. Tests on small datasets are not showing this problem, but we've identified performance issues when archiving page goals for larger datasets which could result in the goals data being incomplete and result in the incorrect value you are experiencing. A performance fix is being worked on at the moment which should hopefully resolve this issue.

@bx80 I'll assign this one to you for now, so you can catch up with @utrautmann one the performance fix is ready and released.

This can also be reproduced in our Matomo reports, shared the details with Ben.