Stats on attribution data clearing

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John Delaney

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Sep 15, 2021, 9:04:51 PM9/15/21
to Attribution Reporting API Dev

Hi all,

Chrome has recently added instrumentation to measure how many attribution reports are removed by browsing data removal in Chrome.

With cookie-based measurement, data deletion after a conversion happens isn't an issue as the ad-tech learns about the attribution immediately at conversion time.

The delayed reporting mechanism in the API means reports are kept on device for longer periods of time and thus are more susceptible to browsing data removal.

In the current Origin Trial for Attribution Reporting we observe:

  • ~6.5% of attributed reports are deleted before they can be sent
  • ~16% of attribution sources are deleted (this includes sources which resulted in reports, and sources which were never associated with reports)

Some, but not all, sources that get deleted are also associated with reports that get deleted. If a source is deleted before the conversion is ever registered, the total loss of reports can be greater than 6.5% when comparing API reports to cookie-based reports. Note that these numbers cover all reports generated by Chrome, and may vary across reporting origins.

You should expect to see differences when comparing API reports and cookie-based reports for these reasons. You may want to divide these into "explained" and "unexplained" gaps using the numbers above.

We have also previously posted numbers for report loss due to network-related errors here.

Happy to clarify any of the above!

John 


Shigeki Ohtsu

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Sep 15, 2021, 10:26:11 PM9/15/21
to John Delaney, Attribution Reporting API Dev
Hi John, sorry, duplicated the mail to you.

Thanks for your investigations and reports.
It is greatly appreciated that we know new findings for the attribution report loss, which comes from the deletions of attribution sources or reports.
What would user actions on Chrome lead to their deletions?
IIRC, Chrome stores the attribution data in a DB file under the user's profile folder. Therefore, the deletion of attribution data would happen when the user removes their profile in Chrome.
Are there others?

Regards,

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John Delaney

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Sep 17, 2021, 2:03:37 PM9/17/21
to Shigeki Ohtsu, Attribution Reporting API Dev
What would user actions on Chrome lead to their deletions?
IIRC, Chrome stores the attribution data in a DB file under the user's profile folder. Therefore, the deletion of attribution data would happen when the user removes their profile in Chrome.
Are there others?

Hi Shigeki,

The scope of data removal we are talking about is described in: https://support.google.com/chrome/answer/2392709?hl=en&co=GENIE.Platform%3DDesktop

"site data" includes the attribution data stored by the API, so the flows described in that link will result in reports being deleted.
 
Thanks,
John

Shigeki Ohtsu

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Sep 21, 2021, 1:29:57 AM9/21/21
to Attribution Reporting API Dev
Hi John,

Thanks. I confirmed that the"Clear data" flag with "Cookies and other site data" removes all stored attribution data.
This flag is enabled by default in the "Basic" settings in the "Clear browsing data" menu, so many users who are trying to clear their browsing history have probably deleted their site data along with it.
As discussed in the conference call yesterday, a small reporting window might be a remedy, and we need to investigate how much it improves in the future OT.

Regards,

2021年9月18日(土) 3:03 John Delaney <john...@chromium.org>:

Maud Nalpas

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Oct 21, 2021, 4:12:35 AM10/21/21
to Attribution Reporting API Dev, shigek...@gmail.com
Hi Shigeki and all,

We've published an FAQ that gives additional context and details on the statistics John shared above:

Let us know in case you have follow-up questions!
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