Area of interest (AOI)

An area of interest, usually AOI, is the geographic area an analysis applies to. It is defined by a boundary, often an administrative one such as a district or municipality, sometimes a drawn polygon or a buffer around something. The GOAT interface calls this the Study Area.

It sounds like housekeeping and it changes results. Anything outside the boundary is invisible to the analysis, which produces edge effects: a supermarket fifty metres beyond the district line does not exist, so the residents nearest to it appear unserved. The standard fix is to compute over a larger area than you report on, then clip the result to the AOI at the end.

For accessibility work specifically, the boundary that matters for the calculation is rarely the boundary you want to report on. People cross municipal lines to shop and to get to school, so an analysis bounded by the municipality will understate what its residents can reach.