Irrigation and Water Resource Management 2011-2012
This evaluation report presents findings from the baseline data collected for the Irrigation and Water Resources Management (IWRM) project, which serves as the primary data source for evaluating the activities of the IWRM project. This report provides an overview of the current irrigation and agricultural situation in the Senegal River Valley. Additionally, the report provides a comparison of treatment and comparison households to check for systematic differences between groups at the time of the baseline survey.
In the IWRM, the selection of areas to receive the project interventions was not random. Rather, it was based on a variety of factors, including political, social and environmental. In the absence of random assignment, we will use a Difference-in-Differences (DID) methodology combined with propensity score matching (DID-PSM) to estimate the impact of the IWRM activities. The baseline data includes community level and household level data. Community level data includes information about regional and socioeconomic characteristics of the village. Household level data sets were collected in 3 waves, one for each agricultural season.
Type de données
Observation data/ratings [obs]
Anonymized dataset for public distribution
The Senegal River Valley (SRV). The SRV is located in the northern part of Senegal, in the delta of the Senegal River and in Podor District.
Habitants in the Senegal River Valley (SRV) in the northern part of Senegal
Three waves of data have been planned for the baseline and follow-up surveys in the Delta and Podor areas to cover the different agricultural seasons.
Producteurs et sponsors
Sponsor / Agence de financement
Millennium Challenge Corporation
To implement the DID analysis, we needed to draw the sample of households for the study from both the treatment and comparison areas. The previous evaluation contractor determined that the sample size needed to estimate the combined impact of the irrigation and land intervention in the Delta was 2,612 households: 1,306 from the treatment area and 1,306 from the comparison area.
For Podor, the sample size was initially constrained by the amount of land available for distribution, i.e. approximately 400 ha. MCA-S expected to distribute approximately 1 ha per household, meaning that the household sample size is approximately equivalent to the number of hectares available for distribution. The final sample size for Podor is 440 households in the treatment area and 440 households in the comparison area.
Ecarts par rapport au plan de sondage
To implement DID with ex-ante matching, households should be matched before the survey. This requires a detailed enumeration in the treatment and comparison areas to collect a set of variables that can match treatment and comparison households. In the spring of 2012, the Agence Nationale de la Statistique et de la Démographie (ANSD) conducted extensive enumeration in the Delta area, including the Saint Louis and Dagana departments, for a total of about 11,600 households. IMPAQ used the enumeration files to sample and match households. The target sample sizes for the Delta were 1,306 treatment households and 1,306 matched comparison households. To achieve this sample size, IMPAQ provided slightly larger samples to ANSD to allow for some non-response because the survey effort may not have reached 100 percent of the sample. Specifically, we selected 1,637 treatment and 1,637 comparison households (about 25 percent more than the proposed sample sizes).
From the enumeration file, we randomly sampled 1,637 treatment households. We then matched each treatment household with a comparison household identified as the most similar in relevant pre-treatment characteristics.
In the spring of 2012, ANSD completed an extensive enumeration in the Podor area. Specifically, 1,617 households were enumerated in the treatment area and 585 were enumerated in the comparison area. For the impact evaluation, it is important that the treatment group include households that will actually get the treatment (irrigation and land). However, at the time of sampling, we could not find a clear way to identify which households would receive irrigated land in Podor. Because the enumeration data includes 1,617 households in the treatment area and we needed to identify the 440 households that would receive land, a random sample would not ensure that we select enough households that actually receive land.
Given the urgency of selecting the samples and proceeding with the survey, MCA-S and IMPAQ agreed to survey all households (1,617) in the enumerated treatment area. This approach ensured that our survey sample would capture the households that would receive land (treatment group). In addition, we agreed to survey a random sample of 440 households in the Podor comparison area (out of a total of 585 households in the enumeration). Moving forward quickly was very important to avoid wasting time and resources. Furthermore, waiting until spring 2014 (when land decisions are expected to be finalized) could have jeopardized our ability to have useful baseline data because the intervention may take place before the baseline data collection.
Collecte des données
Dates de la collecte des données (AAAA/MM/JJ)
Date de début
Date de fin
Collecteurs de données
Agence Nationale de Statistique et de la Démographie