Safari to prevent cross-site tracking

Apple’s “intelligent tracking prevention” (ITP), announced in June 2017 and scheduled for the fall 2017 Safari update, purposes to keep trackers, namely ad trackers and third-party data trackers, from following users as they browse from site to site.

That browsing information data is routinely used for retargeting, interest and other behavioral ad targeting.  Ads themselves aren’t blocked, just the user’s previous browsing data.  Given that Safari accounts for nearly 50 percent of mobile web traffic share in North America, ITP is a big deal relative to mobile ad conversion attribution. It stands to be very disruptive to accurately tracking view-through conversions attributed to display & video campaigns (including remarketing / retargeting), and also with the integrity of interest and other behavioral ad targeting.

Conversion tracking for ad ecosystems like the Google Display Network (or GDN, ads served via AdWords) and the Google Ad Exchange (or AdX, ads served via DoubleClick Campaign Manager among others) is primarily based on third-party cookies.  Clicking, or even simply viewing, an ad from these ecosystems results in a third-party cookie being set on a user’s browser.  Pre-ITP, these ad ecosystems can “see” these third-party cookies for Safari browsing users until the cookies are deleted (i.e., no time limit if the cookie still exists – depending on the view-through conversion window setting), regardless of the website where the ad was viewed or clicked.

These third-party cookies allow attribution for the related ad to any conversions engaged from that browser, on any website (i.e., cross-site tracking).  This in turn allows reporting when a user simply viewing an ad, whether they click or not, influenced a later conversion by that user (if the third-party cookie set when they viewed that ad still exists and is accessible by the system at the time of conversion).  This view-through conversion is also known as an “impression assisted conversion”.  This same tracking method also allows measuring “click assisted conversions”.

With ITP, third-party cookies can only be seen by these systems for 24 hours from the time a user visits a website via Safari.  As such, unless a user converts within that 24 hours window, the conversion attribution will be lost.

Google Analytics helps AdWords ad click tracking on Safari

Starting in September 2017, in response to this Safari update, Google is making changes to the way it captures and reports on conversions in AdWords.  ITP encourages “server-side storage for attribution of ad impressions on your website”.  Google has developed a new Google Analytics cookie that will be used to capture campaign and conversion data from Safari in a way that conforms with ITP:

  1. If AdWords auto-tagging is enabled and Google Analytics is deployed on the website, Google will set a new Google Analytics cookie on that site’s domain, which will store information about the ad click that brought a user to your site.  Where AdWords and Google Analytics accounts have been linked, the AdWords conversion tracking tag will be able to use that click information.
  2. AdWords will continue to report conversions for users who have recently interacted with Google services and domains (i.e., cross-device conversions).
  3. AdWords will also use statistical modeling to estimate website conversions that could not be measured from Safari, and include them in your AdWords reporting.

The new Google Analytics _gac cookie

The new Google Analytics_gac cookie that stores the ad click information when auto-tagging is enabled is a first-party cookie, and therefore is acceptable to ITP.  That means ad data associated with the user will remain intact for attribution and conversion reporting.  But – this fix only works for ad click & click assisted conversions, not impression assisted conversions.

Impact on AdWords conversion reporting

For those that don’t link their AdWords and Google Analytics accounts or disable the new cookie, Google will only be able to record click, click assisted, and impression assisted conversion activity that occurs within the initial 24-hour period.  For anything beyond 24 hours, it will use modeling based on historical conversion activity to record conversions from Safari in AdWords. Those modeled conversions will be included in AdWords conversion columns.

What about impression assisted conversions for Safari users?

The Google Analytics “first-party cookie” fix helps ensure the integrity of click & click assisted conversion reporting in AdWords – and it also can help in the same way regarding cross-device click conversions (made available by Google back-end wizardry).  But, impression assisted conversions are what will heavily lean upon modelling for calculation when it comes to Safari.

Because ad ecosystems will be guessing about impression assisted conversions from Safari browsers (where the user hasn’t logged into a Google account from the browser “recently” relative to the ad click or view), in theory the market should value less Safari impressions / impression assisted conversions.   But, it will take a concerted effort for advertisers to fully consider this phenomenon in their buying decisions.

AdWords Tracking Update in Response to Apple’s Intelligent Tracking Prevention