Google Transparency Report Assessment

In August 2018, Google added a new section about political advertising to its Transparency Report. Initially covering the USA, this section was expanded to the European Union May, 2nd 2019.

This document presents the difficulties and limitations in producing research and analyses based on Google’s transparency data concerning political ads.


The section about political ads of Google’s Transparency Report comprises a dynamic web page to navigate and search through the ads.

The underlying data can also be downloaded as a ZIP file containing CSV files and documentation. Providing this bundle greatly simplifies reuses of this data. In our case, assessing the quality and the consistency of the data provided by Google was much easier than if the data had been available only by an API or a web page.


Advertiser identifier is inconsistent

The documentation explains that “Multiple advertisers may appear if there is more than one funding source for an ad.” However, we also observed that for 65 ads, the advertiser identity changed between June 14th and June 15th 2019, and again between June 18th and June 19th 2019. Previous advertisers are no longer visible either in the bundle nor the web page.

For instance, the ad CR517478000787193856 was initially linked to advertiser AR188817757448437760 (no longer accessible), then to advertiser AR322201712037199872 (no longer accessible), and then to advertiser AR464795176020213760. These 3 advertisers share the same name so we can assume that these 3 accounts are controlled by the same entity. However, the documentation does no explain why the identifier is not constant.

Ads content is not available programmatically

Even though publishing the data as a bundle is a major advantage for research, the provided bundle only contains metadata about the ads and no content.

Ads can be of three types: text, image or video.

  • The textual content can be fetched using an undocumented Google API, which is cumbersome but feasible.
  • We observed that the images are displayed in the web page using, depending on the ad, at least two different technical means involving dynamic scripts, neither of which are easy to reverse engineer.
  • As for the videos, they are displayed by streaming and we did not assess whether the streaming is performed using standard streaming protocols.

Poor data integrity

Content of removed ads is not accessible

The documentation states that:

The content of an ad may not appear if the ad did not comply with Google Ads policies, or when it isn’t available for technical reasons; however, data about the ad remains in the report.

In case of policy violation, the data is indeed replaced by a message:

Policy violation This ad violated Google’s Advertising Policies.

It is thus impossible to retrieve the original content of the ad. Moreover, the clause that was violated is not mentioned, as documented:

Google continuously reviews all ads, including election ads, for compliance with our policies. Any ad found to be non-compliant is labeled as a “Policy Violation” in our report. We do not externally disclose details of which policies advertisers have violated.

Incidentally, the bundle does not reveal which ads were removed and the web page does not allow to search for removed ads, so it is very hard to list which advertisers breached Google policies on political ads.

Unexplained ads removal

We have been regularly downloading the bundle since June 14th 2019 to January 14th 2020. The version of the bundle published June 19th was missing 212 ads. Eleven European advertisers paid for at least one such ad: KKW Lewica Razem – Razem, Unia Pracy, RSS, Asociația Platforma Inițiativa România, Kansallinen Kokoomus r.p., Bündnis 90/Die Grünen Landesverband RLP, Konfederacja KORWiN Braun Liroy Narodowcy, Fratelli d’Italia Centrodestra Nazionale, Bündnis 90/Die Grünen Baden-Württemberg, EVOLVEDREAMSOFT SRL, Sloboda a Solidarita (SaS), Partido Popular Regional De Canarias, Sloboda a Solidarita.

Update (December 2020): A comparison between the bundles from January 14th 2020 and November 31st 2020 shows that while 434.380 ads have been added, 27.937 have been removed in the meantime. During the same timeframe, 82 advertisers have been removed.

Altered weekly spendings

Weekly spendings about 72 advertisers were removed in the bundle dated June 19th, for no understandable reason.

In the same bundle version, 293 figures were changed. For instance, it is reported that the advertiser AR474748779908562944 spent 25,350 € in political ads during the week beginning May 12th 2019, while this figure was 21,100 € in the previous bundle version.

Inconsistent total spendings

For the report to be consistent over time, ads spendings should only increase (or stay the same). However, for some areas in the USA and for Poland, the total spent amount on political ads went down from one report to the next. For example, on the reports dated June 14th and June 18th, the amount of 201,300 € was reported for Poland. However, on June 19th, this amount decreased to 199,200 €.

Update (December 2020): The same test applied from January 14th 2020 to November 31st 2020 shows that the total amount spent decreased for Estonia, Bulgaria and the United Kingdom.