Table 2 summarizes the reach of the various intervention components based on project monitoring data. For TSSM, 407 masons were trained across all treatment villages. A further 282 CLTS facilitators were trained and conducted CLTS triggering in a total of 79 wards.<sup>23</sup> All TSSM villages received murals and/or posters, and 81 out of the 90 originally assigned wards received the DCC event<sup>24</sup> reaching a recorded 180,000 people.

For the HWWS campaign, 433 FLAs were trained across all of the treatment villages. The DCC event missed 5 of the 91 assigned wards, reaching an estimated 220,000 people during the first round and 234,000 in the second round.<sup>25</sup>

# **3. Experimental Design**

# **_3.1._** _Identification Strategy_

Tanzania is administratively separated into 30 regions, 169 districts and 3,643 wards, with the average ward holding approximately 12,000 people. To evaluate the impact of sanitation, handwashing and combined interventions, we implement a cluster-randomized evaluation with random assignment of interventions at the ward level, including a total of 135 intervention and 46 control wards. Wards were identified as the optimal operational unit of implementation for the project, and of sufficient geographic extension to minimize the risk of significant information spillovers between populations exposed to the localized messages, community events, and other forms of social promotion activities.

The sample was drawn from 10 districts spread throughout the country selected by the Ministry of Water (MoW) and Ministry of Health and Social Welfare (MoHSW) to provide geographic diversity at the national level (see map in Figure 6). These districts are not random, and were targeted because of operational feasibility for program implementation, taking into account the existence of ongoing MoW and MoHSW projects, including the Health Village Campaign (HVC) and water and sanitation interventions. Of the 245 wards in these 10 districts, initially 13 wards were dropped from the sample. Three of these wards were urban, and thus ineligible for the program, and the remaining 10 wards were pre-selected as pilot areas for the program and excluded from the evaluation. Among the remaining 232 wards the program selected the 190 largest wards by population size in order to maximize the population under treatment. These 190 wards were subsequently randomly assigned to one of four groups: (1) Handwashing intervention, (2) Sanitation intervention, (3) Handwashing and Sanitation intervention, and (4)

> of the soap opera. We find this had a positive but non-significant increase in recall of the soap opera which was not a large enough effect to be able to measure subsequent impacts of the campaign through the encouragement.

> 23 While 90 wards were assigned to receive CLTS, 11 were not treated due to logistical challenges of district facilitators training and visiting wards, with lack of funds for the district facilitator to travel cited as the reason for non-compliance.

> 24 Imperfect compliance resulted from logistical constraints of reaching villages during the roadshow schedule

> 25 It is not possible to compute how much overlap there was between the first and second round, but it is expected that these numbers mostly reflect repeat exposure since the events were conducted in the same villages in both rounds.

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