1. Watching the watchers: Epstein and Robertson’s „Search Engine Manipulation Effect“
In July, 2015, Epstein and Robertson published a widely acknowledged study on how much a biased search engine result ranking can shift undecided voters towards one candidate . In their abstract, they summarize that “biased search rankings can shift the voting preferences of undecided voters by 20% or more” . In various articles and interviews, Epstein refers to his study and states that “as many as 80% of voters in some demographic groups” can be shifted (e.g. here, in an exclusive article by Epstein himself for Sputnik News ). Many established newspapers and magazines quote the authors’ results, e.g., Sandro Gaycken in an article for the Süddeutsche Zeitung: “Epstein was able to proof that targeted manipulation of the search results for queries with a political topic results in a shift of opinion towards the manipulator. A very effective kind of manipulations, as it seems: more than a quarter of the users changed their opinion.” (“Epstein konnte nachweisen, dass die gezielte Manipulation der Ergebnisse von Websuchen zu politischen Themen in Suchmaschinen eine Meinungsänderung zugunsten des Manipulators bewirkt. Eine sehr effektive Art der Beeinflussung, wie es scheint: Mehr als ein Viertel der Suchenden änderten ihre Haltung.”) .
In this article, I will show that the results are strongly exaggerated because they are based on a measure which sums up the effects of biasing the results for all candidates instead of averaging them or stating the range of possible effects. In the most realistic of the three studies conducted by Epstein and Robertson, the single effects are within the range of 2-4%. This is still an important effect, especially for elections which are as close as the ones often seen in the USA but less worrying for European countries with multiple parties.