administration techniques can reduce sensitivity bias by changing the social context in which sensitive questions are asked so that the identity of the respondent is obscured from interviewers, bystanders, and other potential social referents.

While most of the core topics shared between the PPCS and the Facebook survey could have been considered sensitive, we expect that in this context the questions on conflict exposure and mental health may have been more sensitive than the questions on food insecurity and COVID-19 exposure. Respondents may have perceived the questions on personal exposure to conflict to be sensitive because they brought up memories of traumatic experiences. In the mental health modules, respondents may have perceived questions as sensitive because of the negative attitudes and stigma around mental illness that persist in many parts of the region.<sup>7</sup> Questions about food insecurity may be perceived as sensitive because of their association with poverty, but we expect this sensitivity to be reduced in the specific context of the PPCS because most respondents had participated in the last wave of the Socio-Economic and Food Security Survey and might therefore be accustomed to answering questions about food insecurity. COVID-19 restrictions are not as severe as they were in earlier stages of the pandemic, and surveys about people's experience of COVID have proliferated since early 2020. We might therefore expect the difference in sensitivity bias between the PPCS and the Facebook survey to be more marked in the indicators related to conflict exposure and mental health than in the indicators related to food insecurity and COVID-19 exposure.

# _Hypotheses_

H2a: People tend to underreport conflict exposure, aggressive tendencies, indicators of risk for mental health problems, and symptoms consistent with depression because these are perceived as dangerous or undesirable traits and experiences.

H2b: People are more likely to underreport dangerous or undesirable traits and experiences in an inperson survey than in a self-administered web survey because the interviewer and bystanders are important social referents for respondents.

# _Discussion_

We explore this pair of hypotheses by comparing shares of sensitive responses reported in the Facebook survey and in the PPCS—following the approach of Tandon and Vishwanath (2022). We define sensitive responses for this purpose as the response options that indicate personal exposure to conflict events, stronger aggressive tendencies, higher risk for mental health problems, and more severe depression symptoms. We would expect to see higher shares of these response options chosen in the Facebook survey than in the PPCS.

If sensitivity bias were the strongest mechanism contributing to the differences we observe between the Facebook and PPCS estimates, we might also expect to see larger differences between the two surveys in the shares of sensitive responses to the conflict exposure and mental health questions than in the shares of responses indicating more severe outcomes in the modules we expect to be less sensitive (food insecurity and COVID-19 exposure).

> 7 See for example Alyafei et al (2021) and Elyamani et al (2021) for references to negative attitudes and stigma in regional context, or World Health Organization: Regional Office for the Eastern Mediterranean (n.d.) for reference to stigma in the Palestinian context.

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