Definición Social desirability bias

Frequently, in a survey, sensitive or embarrassing questions concerning such topics as alcoholism, sex or racism are not answered honestly. The social desirability bias is to blame for this phenomenon, which is also called the effect of conformity.

Respondents want to avoid conceding 'deviant' or extreme opinions and attitudes and therefore do not answer honestly.  Instead, respondents would give an answer which they think is socially accepted – in other words 'socially desired'. This effect is true for many issues concerning the values and norms of society.

Another example is the question about favorite TV shows. Those with a positive social connotations are usually favored (news, documentaries); when actual audience ratings speak another language.