The Facebook survey consistently estimated more severe outcomes than the in-person survey The national-level Facebook estimates range from about 14 percent to about 250 percent more severe than their PPCS counterparts (see Table 2). For six of the eight core indicators, the difference in estimates between the two surveys is significant at the 5% level. The direction of difference holds in almost all cases if estimates are disaggregated by region, gender, age category (18 to 34 / 35 and older) or reported exposure to at least one conflict event. Estimates do not appear to be systematically more similar for any of the subgroups created by these disaggregations, except for respondents from Gaza. This finding is discussed in more detail in a later section. Nor does the direction of differences between subgroups in the Facebook survey necessarily match the direction of differences between the same subgroups in the PPCS.

**Table 2: The Facebook survey estimated more severe outcomes than the PPCS across eight core**

**indicators**

||**Indicator**|**Indicator**<br>**range **|<br>**PPCS**<br>**estimate**|**Facebook**<br>**estimate**|<br><sup>**Difference**</sup>|**N**<br>**(combined)**|
|---|---|---|---|---|---|---|
|_1_|_Share of people who report personal_<br>_exposure to at least one conflict event_<br>_(Gaza only)_|0-100%|35.0<br>(3.2)|49.7<br>(8.8)|14.7<br>(9.4)|2937|
|_2_|<sup>_Approximate prevalence of moderate or_</sup>|0-100%|29.0|67.1|38.1|5703|
||_severe food insecurity_||(2.1)|(7.0)|(7.4)||
|_3_|_Average Reduced Coping Strategies Index_|0-56|5.7|20.0|14.3|6408|
||||(0.4)|(2.7)|(2.7)||
|_4_|_Average aggressive tendencies index_|1-5|1.9|2.7|0.8|6791|
||||(0.0)|(0.1)|(0.1)||
|_5_|<sup>_Average risk for mental health problems_</sup><br>_index_|1-4|2.0<br>(0.0)|2.4<br>(0.1)|0.4<br>(0.1)|6779|
|_6_|<sup>_Prevalence of symptoms consistent with_</sup>|0-100%|57.7|87.4|29.8|6837|
||_depression_||(2.2)|(2.6)|(3.4)||
|_7_|_Averae deression smtom severit level_|0-100|54.8|72.8|18.0|6837|
||_g p yp y_||(1.0)|(2.4)|(2.6)||
|_8_|<sup>_Share of people who report at least one_</sup>|0-100%|72.5|82.6|10.1|6808|
||_type of exposure to COVID-19_||(2.2)|(5.8)|(6.2)||

Notes: For all indicators, higher values indicate more severe outcomes. Indicator 2 is based on the Food Insecurity Experience Scale (FIES); Indicator 4 is based on the 12-item short form of the Buss-Perry Aggression Questionnaire (BPAQ-SF); Indicator 5 is based on 12-Item General Health Questionnaire (GHQ-12); Indicators 6 and 7 are based on WHO-5 Well-Being Index (WHO5). See World Bank Group et al (2022) for further detail on indicator choice and construction. All indicators except conflict and COVID exposure include only complete responses to the module; conflict and COVID exposure indicators include partial responses to the module. Clustered standard errors are reported in parentheses.

This systematic difference in overall results could stem from multiple sources. Part of it is likely driven by who makes up the Facebook survey sample. A small fraction of the people who clicked on the Facebook survey link completed the questionnaire, and this sample almost certainly overrepresents people who are relatively more interested in the psychological conditions of Palestinians and the effects of the May 2021 4