esize_m {r4lineups}

Effective Size

Description

Function for computing Effective Size

Usage

esize_m(lineup_table, k, both = FALSE)

Arguments

lineup_table

A table of lineup choices

k

Number of members in lineup. Must be specified by user (scalar).

both

Defaults to FALSE. Returns Tredoux's adjusted effective size estimate.

If TRUE, provides both Malpass's (1981) and Makpass's adjusted (see: Tredoux, 1998) calculations of effective size.

Details

Reduces the size of a lineup from a (corrected) nominal starting value by the degree to which members are, in sum, chosen below the level of chance expectation.

Value

Malpass's original & adjusted estimates of effective size

References

Malpass, R. S. (1981). Effective size and defendant bias in eyewitness identification lineups. Law and Human Behavior, 5(4), 299-309.

Malpass, R. S., Tredoux, C., & McQuiston-Surrett, D. (2007). Lineup construction and lineup fairness. In R. Lindsay, D. F. Ross, J. D. Read, & M. P. Toglia (Eds.), Handbook of Eyewitness Psychology, Vol. 2: Memory for people (pp. 155-178). Mahwah, NJ: Lawrence Erlbaum Associates.

Tredoux, C. G. (1998). Statistical inference on measures of lineup fairness. Law and Human Behavior, 22(2), 217-237.

Tredoux, C. (1999). Statistical considerations when determining measures of lineup size and lineup bias. Applied Cognitive Psychology, 13, S9-S26.

Wells, G. L.,Leippe, M. R., & Ostrom, T. M. (1979). Guidelines for empirically assessing the fairness of a lineup. Law and Human Behavior, 3(4), 285-293.

Examples

#Data:
lineup_vec <- round(runif(100, 1, 6))

#Call:
esize_m(lineup_vec, 6, both = TRUE)
esize_m(lineup_vec, 6)