Many people underreport embarrassing behaviours and thoughts on surveys. They want to look good, even though most surveys are anonymous. This is called social desirability bias. An important paper in 1950 provided powerful evidence of how surveys can fall victim to such bias. Researchers collected data, from official sources, on the residents of Denver: what percentage of them voted, gave to charity, and owned a library card. They then surveyed the residents to see if the percentages would match. The results were, at the time, shocking. What the residents reported to the surveys was very different from the data the researchers had gathered. Even though nobody gave their names, people, in large numbers, exaggerated their voter registration status, voting behaviour, and charitable giving.
What can we learn about ourselves from the things we ask online? US data scientist Seth Stephens‑Davidowitz analysed anonymous Google search results, uncovering disturbing truths about our desires, beliefs and prejudices.