NCJ Number
182545
Date Published
2000
Length
18 pages
Annotation
This chapter examines the uses of standard deviational ellipses (SDEs) in understanding program and project effects in crime analysis.
Abstract
An SDE is a graphic representation of the co-point variation of observations about major and minor axes in two-dimensional space. This graphic has many advantages compared to other depictions of spatial data. It describes the distribution in two dimensions rather than one, as does the standard radium, and it does not make the same level of assumptions about the two-dimensional distribution as do other statistics. Also, the ratio of the major axis variation to the minor axis variation produces a statistic, the coefficient of circularity, that describes the degree of linearity in the two-dimensional distribution. The research reported here analyzes an intervention to determine whether a change in one variable affects the distribution of another variable, using burglaries as the targeted crime. The global analysis attempted to determine whether the distribution of burglaries in the Bronx changes when school is not in session compared to when school is in session. The analysis notes both the potential and impediments of using SDEs for spatial crime analysis. 4 figures, 12 notes, and 18 references