this oversubscribed list. Selection into the training group was based on a “vulnerability score” that gave priority to younger, female and unemployed individuals. Despite this approach, intake was “fuzzy” - participants were ordered by their vulnerability score, with the most vulnerable entering up until capacity. In some intakes, individuals with comparatively high scores were not taken into the program. In others, individuals with comparatively low scores were included. We construct our treatment and control groups from these intake decisions. Data were collected from members of the host and refugee communities in each country.<sup>4</sup> In both Jordan and Lebanon, the intervention was implemented on a rolling basis. As soon as one training cycle was completed, another would begin. Data were collected in three waves during each training cycle. First, during an “outreach” phase, where data were collected in order to assign treatment status. Second, at “baseline”, which occurred before the training had begun but after treatment assignment was known. Third, data were collected at “endline”, immediately following the end of the training. Data collection for those assigned to the treatment and control followed the same pattern.<sup>5</sup> Outreach and baseline data collection took place less than a week apart and were collected between July 2018 and September 2019. Between outreach and baseline, one full survey round was collected due to potential survey fatigue and on the understanding that nothing of importance would likely change in such a short period. Basic demographic information, such as age, gender, marital status and employment status were collected at outreach. At baseline, additional indicators were collected, relating to the behavior, attitudes, opinions and personalities of the participants. The only exception to this is data on optimism, which were collected at both outreach and endline. This allowed us to test whether or not the intake decision had effects, even before the training began. Endline data were collected between July 2018 and November 2019 and repeated the combined outreach and baseline surveys and experiments.

_Variables:_ We collected a range of survey and experimental indicators in order to assess our key research questions and associated hypotheses:<sup>6</sup>

**Economic and life optimism** : We collected two survey questions about optimism at outreach, baseline and endline. These questions ask individuals to rank their expectation that their life and economic situation will be better in one year than it is now. Answers are

> 4 In addition, data were collected from Palestinian Refugees in Lebanon (PRL). Due to our research design and the complexity of introducing a third grouping who would play outgroup in the behavioral experiments regardless of partner identity, we exclude PRL from the main analyses presented here.

> 5 Data were also collected six months after the end of the training but this was heavily disrupted due to the outbreak of the COVID-19 pandemic. In Lebanon, this resulted in a change to the method of data collection (from in-person to telephone) and in Jordan, an end to data collection entirely. In Jordan, this had a more pronounced effect on the control group, due to the scheduling of data collection and implementation of restrictions in Jordan. Given these complexities, we do not present results from these analyses.

> 6 In addition, we attempted to collect information on the extent of social and economic interactions between hosts and refugees. At baseline, almost 95% of respondents in both the treatment and control group reported such interactions. For this reason, we do not include this information in these analyses.

9