Reducing response bias in reports of trauma and posttraumatic stress disorder: An application of the nonverbal response card in a survey of youth in Burkina Faso.

Response bias for sensitive questions in face-to-face interviewer-administered surveys is a common problem. Our objective was to evaluate the effectiveness of the nonverbal response card (NVRC) in soliciting responses to questions about lifetime trauma exposure and posttraumatic stress disorder (PTSD) symptoms. A sample of youths in Burkina Faso (N = 1,644, age range: 12-20 years) was randomized to answer sensitive questions, including on trauma exposure and PTSD, using either the standard verbal method or the NVRC, a laminated two-sided card that allows respondents to nonverbally answer questions without the interviewer knowing the actual response. We compared reported trauma exposure and PTSD prevalence, internal consistency, and convergent validity by response method. Compared with verbal respondents, NVRC respondents reported lifetime exposure to 18.0% more trauma types and were 2.8 times as likely to report three or four PTSD symptoms, with female trauma reports and male PTSD reports most affected. Measures of internal reliability and convergent validity were also higher for the NVRC method compared to verbal responses, trauma exposure (15 items): Cronbach's αs = .84 vs. .60, PTSD symptoms (four items): Cronbach's αs = .71 vs. .52. Due to the shame that is often associated with trauma and mental health disorders, standard interviewing approaches that rely on verbal responses are likely to underenumerate trauma exposure and PTSD, particularly among refugees who have low trust in formal authorities and institutions. The NVRC offers a low-tech, low-cost method that does not require literacy, is highly portable and robust, and offers enhanced privacy.