Mode of administration and interviewer effects in self-reported symptoms of anxiety and depression

This study investigates whether mode of administration and the interviewer's age and sex affect results obtained with a commonly used rating scale for symptoms anxiety and depression (HSCL-25). Identical versions of the scale was administered orally by experienced interviewers, either face-to-face or by phone. Another sample received self-administered questionnaires that were completed at home and returned by mail. Subjects were a total of 13,850 Norwegian adults participating in two broad population surveys. Results seem to confirm the standing presumption that in-person interviews are more vulnerable to socially desirable responding (SDR) than self-administered modes: Two to three times as many "probable cases" of psychological distress are identified with the self-administered mode compared to the interview modes. However, the SDR generated by mode of administration apparently occurs in subgroups of respondents not identified by extant measures of social desirability (the Crowne-Marlowe scale, etc.) as being high on SDR: In the present study the young and well-educated respondents appear particularly prone to under-report symptoms with the interview modes. The impact of sex and age of interviewer on symptom reports generally appears weak. However, young male interviewers receive very few symptom reports compared to other interviewers.