We will address these research questions in the context of Indian slums in the cities of Lucknow and Kanpur (Uttar Pradesh, India) using a randomized-controlled trial (RCT) design. Figure 1 shows the study area. We will randomly select 110 catchment areas of CTs in both cities and we will allocate them to one of three experimental arms. Catchment areas will then be allocated to one these three groups:
2. Supply-side intervention
3. Supply side intervention plus Information provision
Randomization into these groups will be carried out at the cluster level, specifically the CT catchment area level. Randomizing at the cluster level has the advantage that we can limit contamination of the control group, especially considering the possible spread of the information that will be provided. This is of particular relevance for answering research questions around longer-term behaviour (particularly usage of sanitation facilities).
To allocate clusters to treatment arms, we will stratify the sampled clusters by the main company who owns the CTs (versus other owners) and by city of study (Lucknow and Kanpur). We will then build blocks of 3 CTs using m-distance (Mahalanobis) relative proximity. To construct m-distances, we will make use of the rich census information we collected, including CT and slum-dweller characteristics. After forming blocks of similar clusters (CTs), we will randomly allocate each CT in a block to either treatment 1, treatment 2 or the control group. Each one of the three possibilities will have the same probability.
In our study, a cluster is a CT catchment area. We identified catchment areas by first mapping all CTs in our study cities. Out of these, we chose a subset of CTs to become part of the study, based on the following criteria:
1. The CT has to be pay-to-use;
2. It has to be located close to a residential area (slum) and used by residents.
We drop CTs for which the distance to another CT is limited. In particular, there should be sufficient distance between two CTs to avoid users switching between CTs (possibly driven by their treatment status). We drop CTs that are closer than 300 meters to each other, and CTs that have two other CTs closer than 350 meters.
In addition, we drop CTs in whose catchment areas fewer than eight eligible households are living. A household is considered eligible if the following conditions are respected:
1. The household lives in the catchment area of a selected CT, which is broadly defined as slum area within 250 meters from the CT building. Households are linked to CTs based on geo-coordinates collected during the census.
2. At least one household member uses a CT or shared toilets (i.e. neighbours, makeshift, work, school), or practices open defecation.
3. The household must have reported during the census interview not to intend to migrate during the following 18 months (i.e. until the planned study endline survey). We will focus on these households to reduce the risk of attrition.
Within each of the selected study CTs and their catchment areas, we will sample up to 17 eligible households (if available), aiming for an average of 15 households per cluster. Given that distance is a major determinant of CT usage, we will focus on eligible households living closer to the CT (within 150 meters). Since some CTs have more dispersed populations, we will conduct a two-step sampling procedure. First, in large-population catchment areas (where 10 or more households are available within 150 meters), we will sample only from households that are located within this bound. Second, in small-population CTs (where less than 10 households are available within 150 meters), we will first sample all households within 150 meters and randomly selected the remaining households from those that are located between 150 and 250 meters from the CT. We aim to interview 1,650 households in 110 randomization units (catchment areas of CTs) and one CT caretaker per randomization unit.
The main respondent for the household survey will be an adult household member – likely the household head, spouse or other knowledgeable household member – who should fall in the age range of 18-64 years. We will further interview the spouse of the household head, aiming to collect information on WTP from one male and one female household member. In households with children aged 5 years or younger, we will further interview the primary caregiver to collect information on child health and sanitation practices.
The main respondent for the CTs (supplier survey) will be the caretaker.