In social science research, social desirability bias is a type of response bias that is the tendency of survey respondents to answer questions in a manner that will be viewed favorably by others. It can take the form of over-reporting "good behavior" or under-reporting "bad", or undesirable behavior. The tendency poses a serious problem with conducting research with self-reports, especially questionnaires. This bias interferes with the interpretation of average tendencies as well as individual differences.
Topics where socially desirable responding (SDR) is of special concern are self-reports of abilities, personality, sexual behavior, and drug use. When confronted with the question "How often do you masturbate?", for example, respondents may be pressured by the societal taboo against masturbation, and either under-report the frequency or avoid answering the question. Therefore, the mean rates of masturbation derived from self-report surveys are likely to be severe underestimates.
When confronted with the question, "Do you use drugs/illicit substances?" the respondent may be influenced by the fact that controlled substances, including the more commonly used marijuana, are generally illegal. Respondents may feel pressured to deny any drug use or rationalize it, e.g. "I only smoke marijuana when my friends are around." The bias can also influence reports of number of sexual partners. In fact, the bias may operate in opposite directions for different subgroups: Whereas men tend to inflate the numbers, women tend to underestimate theirs. In either case, the mean reports from both groups are likely to be distorted by social desirability bias.
Other topics that are sensitive to social desirability bias:
The fact that people differ in their tendency to engage in socially desirable responding (SDR) is a special concern to those measuring individual differences with self-reports. Individual differences in SDR make it difficult to distinguish those people with good traits who are responding factually from those distorting their answers in a positive direction.
When SDR cannot be eliminated, researchers may resort to evaluating the tendency and then control for it. A separate SDR measure must be administered together with the primary measure (test or interview) aimed at the subject matter of the research/investigation.The key assumption is that respondents who answer in a socially desirable manner on that scale are also responding desirably to all self-reports throughout the study.
In some cases the entire questionnaire package from high scoring respondents may simply be discarded. Alternatively, respondents' answers on the primary questionnaires may be statistically adjusted commensurate with their SDR tendencies. For example, this adjustment is performed automatically in the standard scoring of MMPI scales.
The major concern with SDR scales is that they confound style with content. After all, people actually differ in the degree to which they possess desirable traits (e.g. nuns versus criminals). Consequently, measures of social desirability confound true differences with social-desirability bias.
Until the 1990s, the most commonly used measure of socially desirable responding was the Marlowe-Crowne Social Desirability Scale. The original version comprised 33 True-False items. A shortened version, the Strahan-Gerbasi only comprises ten items, but some have raised questions regarding the reliability of this measure.
In 1991, Delroy L. Paulhus published the Balanced Inventory of Desirable Responding (BIDR): a questionnaire designed to measure two forms of SDR. This forty-item instrument provides separate subscales for "impression management", the tendency to give inflated self-descriptions to an audience; and self-deceptive enhancement, the tendency to give honest but inflated self-descriptions. The commercial version of the BIDR called "Paulhus Deception Scales (PDS)".
"Extreme response style" (ERS) takes the form of exaggerated extremity preference, e.g. for '1' or '7' on 7-point scales. Its converse, 'moderacy bias' entails a preference for middle range (or midpoint) responses (e.g. 3-5 on 7-point scales).
"Acquiescence" is the tendency to prefer the higher ratings over lower ratings, whatever the content of the question.
These kinds of response styles differ from social desirability bias in that they are unrelated to the question's content and may be present in both socially neutral and in socially favorable or unfavorable contexts, whereas SDR is, by definition, tied to the latter.
When the subjects' details are not required, as in sample investigations and screenings, anonymous administration is preferably used as the person does not feel directly and personally involved in the answers he or she is going to give.
Anonymous self-administration provides neutrality, detachment and reassurance. An even better result is obtained by returning the questionnaires by mail or ballot boxes so as to further guarantee anonymity and the impossibility to identify the subjects who filled in the questionnaires.
A further method to assess the prevalence of socially sensitive issues is the so-called randomized response technique. Therein, for example, respondents secretly throw a coin and respond "yes" if it comes up heads, and are instructed to respond truthfully (e.g. drug abuse) if it comes up tails. This enables the researcher to estimate the actual prevalence of the given behavior without needing to know the true state of an individual respondent.
SDR tends to be reduced by wording questions in a neutral fashion. Another is to use forced-choice questions where the two options have been equated for their desirability.
One approach is to administer tests through a computer (self-administration software). A computer, even compared to the most competent interviewer, provides a higher sense of neutrality as it does not appear judgmental.
The most recent approach--the over-claiming technique--assesses the tendency to claim knowledge about non-existent items. More complex methods to promote honest answers include the randomized response and unmatched count techniques, as well as the bogus pipeline technique.