Modifiable areal unit problem
The modifiable areal unit problem (MAUP) is a source of statistical bias that can radically affect the results of statistical hypothesis tests. It affects results when point-based measures of spatial phenomena (e.g. population density) are aggregated into districts. The resulting summary values (e.g. totals, rates, proportions) are influenced by the choice of district boundaries. For example, census data may be aggregated into census enumeration districts, or postcode areas, or police precincts, or any other spatial partition (thus, the "areal units" are "modifiable").
The issue was discovered in 1934 and later described in detail by Stan Openshaw, who lamented that "the areal units (zonal objects) used in many geographical studies are arbitrary, modifiable, and subject to the whims and fancies of whoever is doing, or did, the aggregating."
- Gehlke, C. E.; Biehl, Katherine (March 1934). "Certain effects of grouping upon the size of the correlation coefficient in census tract material". Journal of the American Statistical Association 29 (185A): 169–170. doi:10.2307/2277827.
- Openshaw, Stan (1983). The modifiable areal unit problem. Norwick: Geo Books. ISBN 0860941345. OCLC 12052482.
- Cressie, Noel A (1996). "Change of support and the modifiable areal unit problem". Geographical Systems 3 (2–3): 159–180.
- Holt, David; Steel, David; Tranmer, Mark; Wrigley, Neil (July 1996). "Aggregation and ecological effects in geographically based data". Geographical Analysis 28 (3): 244–261. doi:10.1111/j.1538-4632.1996.tb00933.x.
- Kwan, Mei-Po (2012). "The uncertain geographic context problem". Annals of the Association of American Geographers 102 (5): 958–968. doi:10.1080/00045608.2012.687349.
- Unwin, David J (December 1996). "GIS, spatial analysis and spatial statistics". Progress in Human Geography 20 (4): 540–551. doi:10.1177/030913259602000408.
- Wong, David (2009). "The modifiable areal unit problem (MAUP)". In Fotheringham, A Stewart; Rogerson, Peter. The SAGE handbook of spatial analysis. pp. 105–124. ISBN 9781412910828. OCLC 85898184.
- Wrigley, Neil (1995). "Revisiting the modifiable areal unit problem and the ecological fallacy". In Cliff, Andrew D. Diffusing geography: essays for Peter Haggett. The Institute of British Geographers special publications series 31. pp. 123–181. ISBN 0631195343. OCLC 30895028.