Social desirability bias
Social desirability bias is the tendency of 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:
- Personal income and earnings, often inflated when low and deflated when high.
- Feelings of low self-worth and/or powerlessness, often denied.
- Excretory functions, often approached uncomfortably, if discussed at all.
- Compliance with medicinal dosing schedules, often inflated.
- Religion, often either avoided or uncomfortably approached.
- Patriotism, either inflated or, if denied, done so with a fear of other party's judgement.
- Bigotry and intolerance, often denied, even if it exists within the responder.
- Intellectual achievements, often inflated.
- Physical appearance, either inflated or deflated
- Acts of real or imagined physical violence, often denied.
- Indicators of charity or "benevolence," often inflated.
- Illegal acts, often denied.
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 measure of SDR 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 comprises only 10 items, but some have raised questions regarding the reliability of this measure.
In 1991, Delroy L. Paulhus published the Balanced Inventory of Desirable Responding: a questionnaire designed to measure two forms of SDR. This 40-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)", ".
Other response styles
'Extreme response bias' (ERB) 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.
Anonymity and confidentiality
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.
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: it does not appear to be judging.
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.
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- Thompson, E. R. & Phua, F. T. T. 2005. Reliability among senior managers of the Marlowe-Crowne short-form social desirability scale, Journal of Business and Psychology, 19, 541-554.
- Paulhus, D.L. (1991). Measurement and control of response biases. In J.P. Robinson et al. (Eds.), Measures of personality and social psychological attitudes. San Diego: Academic Press
- Paulhus D.L., (1998) Paulhus Deception Scales (PDS) is published by Multi-Health Systems of Toronto.
- Roccato M., (2003) Desiderabilità Sociale e Acquiescenza. Alcune Trappole delle Inchieste e dei Sondaggi. LED Edizioni Universitarie, Torino. ISBN 88-7916-216-0
- Stoeber, J. (2001). The social desirability scale-17 (SD-17). European Journal of Psychological Assessment, 17, 222-232.
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- McBurney D.H., (1994) Research Methods. Brooks/Cole, Pacific Grove, California.