The remainder of the paper proceeds as follows. Section 2 describes the experiment. Section 3 presents the empirical model. Section 4 reports the main results, highlighting how much participants decided to give, which delivery option encouraged more giving, how the transparency-enhancing treatment affected preferences for giving, and how trust and age affected the impact of the treatment and the relative preferences across the different program designs. Section 5 discusses alternative explanations for the increase in giving because of a transparency shock and checks the robustness of the estimates of the interaction between treatment and trust. Section 6 concludes.

# 2 Research design and data

## 2.1 Sample design and selection

The Jordan Gives experiment was carried out with 420 participants in 21 PSUs in Jordan, on a nationally representative sample of the Jordanian middle class. Participants were identified through a three-stage process: (1) 21 PSUs were drawn from a sampling frame of middle-class enumeration areas in Jordan based on the 2004 census; (2) within each PSU, households were selected using a random walk method; and (3) adults were recruited (one per household) to participate in the experiment using a Kish (1949) table. Based on extensive piloting, a protocol was devised to ensure that two groups of 10 randomly assigned individuals each could be constituted in each PSU (10 for treatment, 10 for control) at the same time and place (see Annex 1 for more details).

At the recruitment stage, the invitation letter explained that all participants who appear at the specified place and time (usually a local public school the day after recruitment) would receive a fuel voucher of JD 5 (about US$7.50) as a show-up fee and that there would be a chance to keep JD 10 more in such vouchers, depending on the outcome of the meeting. These vouchers were issued by Jordan Petroleum Refinery Company. They were widely known in Jordan and could be exchanged for gasoline in petrol stations throughout the country. The value of the JD 10 voucher was equivalent to slightly more than the daily minimum wage, or about five days of participants’self-reported mean per capita household expenditure. Each invitee who agreed to participate was left with two receipts (one for the JD 5 voucher and the other for the JD 10 vouchers), which they were of the transfer, the government also decided to set up a National Unified Registry (NUR) of the poor and vulnerable as a common platform for eligibility for social assistance programs, with several checks of living standards. Similar instruments (e.g. Cadastro Unico in Brasil, Ficha de proteccion social/Registro social de hogares in Chile) have been the backbone of transparent social assistance programs around the world (see Silva, Levin, and Morgandi 2013; Lindert et al. 2007; and Ministry of Social Development of Chile 2015). Many other developing countries have, in recent years, accompanied subsidy reforms by measures to enhance transparency. This includes, for example, earmarking increased funding for education and infrastructure linked to fiscal savings from subsidy reform, creating a website where each person could compute his/her score or enter their national ID and verify his/her (in)eligibility/information, or displaying the list of social assitance beneficiaries in a public place (IMF 2013).

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