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Asymptotic Variance of Log Diagnosticity

Source: R/var_d.R
var_diag_ratio.Rd

Computes the large-sample variance of the log diagnosticity ratio for a lineup pair.

Usage

var_diag_ratio(lineup_pres, lineup_abs, pos_pres, pos_abs, k1, k2)

Arguments

lineup_pres

A numeric vector of lineup choices for a lineup in which the target was present

lineup_abs

A numeric vector of lineup choices for a lineup in which the target was absent

pos_pres

A scalar, representing target position in TP lineup. Must be declared by user

pos_abs

A scalar, representing target position in TA lineup. Must be declared by user

k1

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

k2

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

Details

Returns 1/h - 1/N_TP + 1/f - 1/N_TA for positive suspect-ID counts h and f. This is on the log-ratio scale, as in Tredoux (1998), not the raw ratio scale. A delta-method variance for the raw ratio is the squared diagnosticity ratio times this value.

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_pres <- round(runif(100, 1, 6))
lineup_abs <- round(runif(100, 1, 6))
pos_pres <- 3
pos_abs <- 4

#Call:
var_d <- var_diag_ratio(lineup_pres, lineup_abs, pos_pres, pos_abs, 6, 6)
var_d <- var_diag_ratio(lineup_pres, lineup_abs, 3, 4, 6, 6)