Simple Spatial Sampling Method or S3M is a development of CSAS for very wide area usage including national level surveys. The key features of S3M
- Sampling points using a triangular irregular network (TIN) rather than a grid
- Highly efficient use of data (c. 6 × reuse of data)
- Lower cost than CSAS (10 x area for 2 × cost)
- Maps a ‘coverage surface’
- Automatic smoothing of data
- Simple to understand
S3M uses a two-stage sampling design. The first stage is a systematic spatial sample using a triangular irregular network rather than a grid to identify communities to sample. The second stage is active and adaptive case-finding as with the other coverage survey methods.
S3M provides the following outputs:
- Coverage map similar to that of CSAS
- Overall estimate of coverage
- Ranked list of barriers to access
Guevarra, E et al, 2012. Report on the Simple Spatial Sampling Method (S3M) survey conducted in Tillaberi, Dosso, Tahoua, Maradi and Zinder regions of Niger. Valid International, Oxford
Guevarra, E and Siling, K, 2013. Report on the Simple Spatial Sampling Method (S3M) pilot in Wolayita Zone, Southern Nations, Nationalities and Peoples’ Region and South Wollo Zone, Amhara Region, Ethiopia. Valid International, Oxford.