Embedded Files
Figure 1: Sampling Grid Example. The grid on the map above has 20 intersections. At each intersection (blue dot), 5 household surveys would be completed to give a total of 100 surveys. At each orange point, 1 environmental sample of each pathway would be collected to provide a total of 10 samples per pathway throughout the neighborhood.
GIS-Based Survey and Sample Collection Planning
GIS-Based Survey and Sample Collection Planning
Developing Sampling Maps
• Mapping a study area (neighborhood, community, etc.) is an essential starting point of conducting a SaniPath Exposure Assessment
• The maps of each study site will be used to delineate the areas eligible for inclusion in data collection activities and provide guidance for the geographic area that needs to be covered to provide accurate estimates for risk for each community
• GIS software (ArcGIS, Qgis, or others) should be used to develop satellite or street-level maps that show both the boundaries of a neighborhood as well as a sampling grid that is overlaid over the data collection area
• The sampling grid should be designed to a scale at which at least 10 intersections fall within the neighborhood boundaries (see Figure 1)
Household Selection for Surveys
• Maps of the study area should be used to ensure spatial distribution of household surveys throughout the neighborhood
• A grid will be placed over the map to determine starting points for household surveys (Figure 1, blue dots)
• Based on the size of the neighborhood and the grid, a set number of surveys will be conducted at each point following the procedure below:
- A household will be selected at random to begin the first survey
- After finishing, teams will move along at a regular interval (every 8 households, for example) and conduct further surveys until the required amount is complete
Environmental Sample Collection
• Maps of the study area will be used to ensure spatial distribution of environmental samples throughout the neighborhood
• A grid will be placed over the map to determine starting points for environmental samples (Figure 1, orange dots)
• Based on the size of the neighborhood and the grid, a set number of samples will be collected at each point following the procedure below:
- For each environmental pathway, samples will be collected near the grid intersection based on availability and interactions with community members at each point
- For specific pathways such as drinking water, raw produce, and surface water, sample collection staff may ask community members where the most popular sources of water (communal taps, borehole pumps), raw produce (markets, produce stands), or surface water spots (lake, river pond) are located to collect samples from these specific points
Google Sites
Report abuse