Modifiable Areal Unit Problem Definition

modifiable areal unit problem

[spatial analysis] Also known by the acronym MAUP. A statistical bias that can occur during spatial analysis of aggregated data that causes differing results although the same analysis is applied to the same data. MAUP takes two forms: the scale effect and the zone effect.
The scale effect exhibits different results when the scale of the aggregation units is changed. For example, analysis using data aggregated by county will differ from analysis using data aggregated by census tract. Often the resulting difference is valid based on the distinctions of scale.
The zone effect is observed when the scale of analysis is fixed, but the shape of the aggregation units is changed. For example, analysis using data aggregated into one-mile grid cells will differ from analysis using one-mile hexagon cells. The result is a problem because it is an analysis, at least in part, of the aggregation scheme rather than of the data itself.