Both Google Search and Google Scholar more often than not ranked a link to the original article higher than a link indicating that the article has been retracted

The Dissemination of Scientific Fake News: On the Ranking of Retracted Articles in Google. Emmanuel Genot, Erik J Olsson. Jun 2021. Chapter in The Epistemology of Fake News. Oxford University Press (forthcoming Aug 2021, https://www.amazon.com/Epistemology-Fake-News-Engaging-Philosophy/dp/0198863977). https://www.lunduniversity.lu.se/lup/publication/c395d114-c3b2-486a-80a0-0c80c150adee

Summary: Fake news can originate from an ordinary person carelessly posting what turns out to be false information or from the intentional actions of fake news factory workers, but broadly speaking it can also originate from scientific fraud. In the latter case, the article can be retracted upon discovery of the fraud. A case study shows, however, that such fake science can be visible in Google even after the article was retracted, in fact more visible than the retraction notice. We hypothesize that the reason for this lies in the popularity-based logic governing Google, in particular its foundational PageRank algorithm, in conjunction with a psychological law which we refer to as the “law of retraction”: a retraction notice is typically taken to be less interesting and therefore less popular with internet users than the original content retracted. We conduct an empirical study drawing on records of articles retracted due to fraud (fabrication of data) in the Retraction Watch public database. The study tests the extent to which such retracted scientific articles are still highly ranked in Google –and more so than information about the retraction. We find, among other things, that both Google Search and Google Scholar more often than not ranked a link to the original article higher than a link indicating that the article has been retracted. Surprisingly, Google Scholar did not perform better in this regard than Google Search. We also found cases in which Google did not track the retraction of an article on the first result page at all. We conclude that both Google Search and Google Scholar runthe risk of disseminating fake science through their ranking algorithms.