bjtc

Bayesian journey to crime

R

bjtc(pj, od, dest)

Combines a journey-to-crime surface over origin zones with an origin-destination matrix of solved offences (Levine 2009; Levine and Block 2011): P(Jtc), the surface; P(O), the origins of all solved offences; P(O|Jtc), the origins of offences in the zones where the series happened; their product, Bayes’ numerator with the surface as prior; and the risk, the product over P(O), renormalised. Each block sums to 1. The matrix describes past solved offences and inherits their selection.

Parameters

pj

The journey-to-crime value of each origin zone: numbers from 0, not all 0.

od

The origin-destination counts: a matrix with one row per origin zone and one column per destination zone, numbers from 0.

dest

The destination zone (column of od) of each incident of the series: whole numbers from 1; repeats count.

Returns

A data frame with one row per origin zone: pj, po, pod, prod and risk (0 where po is 0).

References

Levine, N. and Block, R. (2011). Bayesian journey-to-crime estimation: an improvement in geographic profiling methodology. The Professional Geographer, 63(2), 213-229. doi:10.1080/00330124.2010.547152

Examples

od <- matrix(c(5, 1, 0, 2, 4, 1, 0, 1, 6), 3)
bjtc(pj = c(0.5, 0.3, 0.2), od = od, dest = c(1, 2, 2))

Generated from the R help page: bjtc in the R reference.