The broad objective of the IE is to estimate the causal impact of the HW and TSSM interventions on the health and welfare of the rural poor in Tanzania. The IE will also, where feasible, test innovative programmatic design components to inform the GoT on operational questions that can help optimize the use of resources as the HW and TSSM approaches are taken to scale.


In the context of the global Gates-funded program of HW and TSSM (including Peru, Senegal, India, Vietnam, and Indonesia), Tanzania is the only country in the wider program of evaluation to include both types of interventions in the same environment. Therefore, a key component of the IE in Tanzania is testing the effects of combined HW and TSSM interventions (interaction effects).


Other elements under consideration for examination in the IE include geographic intensity, frequency of treatment, and types of HW and TSSM promotion activities.

The proposed IE uses a cluster-randomized experimental design, whereby the interventions are randomly assigned to a sub-set of intervention clusters within 10 treatment districts. The sampling process for the randomized IE design was completed in three stages. First, 10 districts were chosen by the Ministry of Water (MoW) and Ministry of Health and Social Welfare (MoHSW) in agreement with the WSP (see Appendix 1). These 10 treatment districts were selected because of operational feasibility for the rapid roll-out of the pilot phase of the project. While the 10 selected districts present a geographically diverse set of areas, the selection was non-random.


Second, within the 10 treatment districts, 200 eligible wards were selected, and randomly assigned to one of four groups:

(1) Handwashing intervention

(2) Sanitation intervention

(3) Handwashing and Sanitation intervention, and

(4) Control (non-intervention).


In a third stage, clusters of minimum-cost efficient units of intervention will be identified within the 200 evaluation wards. A random sample of 200 to 250 clusters will be selected, with 47 or 48 clusters assigned to each of the three treatment groups (47 Handwashing, 47 Sanitation, 48 Handwashing and Sanitation), and up to 100 clusters assigned to the control group.