Research methods
Social desirability bias
People's tendency to give the answer that makes them look good rather than the true one, for example over-reporting how often they exercise or read.
Respondents want to appear sensible, healthy, generous and competent, especially when a researcher is watching. Questions about money, health, habits and competence are most affected.
It can be reduced by asking about specific past behaviour rather than general habits, guaranteeing anonymity, and avoiding wording that makes one answer sound more virtuous.