Figure 2.

Using WorldPop to inform the size and estimated population within each cluster. Left, Square grid overlaid on the WorldPop raster in the Enterics for Global Health––Kenya study site. In this example, the average grid square has an estimated population of approximately 3.5 persons. Right, A total of 144 grid squares (fine blue lines) were combined to reach an average estimated population of 500 people per cluster (bold red lines). It was determined that clusters should be composed of 12 grid squares by 12 grid squares after iteratively calculating the optimum size using the equation, (500/p) × No. of input cells, where p is the mean population of input cells (which can be WorldPop grid squares or clusters from a prior iteration of the calculation). To ensure that clusters have a square aspect ratio, we took the square root of the number of required input cells and rounded it to the nearest whole number.