R: Simulate rwg values from a random null distribution
rwg.sim
R Documentation
Simulate rwg values from a random null distribution
Description
This function is based on the work of Dunlap, Burke & Smith-Crowe (2003). The function draws data
from a random uniform null distribution, and calculates the within group agreement measure
rwg for single item measures as described in James, Demaree & Wolf (1984). By repeatedly
drawing random samples, a distribution of the rwg is generated. The sampling
distribution can be used to calculate confidence intervals for different combinations of group
sizes and number of response options (A).
Usage
rwg.sim(gsize, nresp, nrep)
Arguments
gsize
Group size upon which to base the rwg simulation.
nresp
The number of response options (e.g., there would be 5
response options if using Strongly Disagree, Disagree, Neither, Agree, Strongly Agree).
nrep
The number of rwg values to simulate. This will generally be 10,000 or more,
although the examples use nrep of 1000 to make the calculations fast.
Value
rwg
rwg value from each simulation.
gsize
Group size used in the rwg simulation.
nresp
Simulated number of response options.
nitems
Will always be 1 for an rwg estimate.
rwg.95
Estimated 95 percent confidence interval. Values
greater than or equal to rwg.95 are considered significant, p<.05.
Cohen, A., Doveh, E., & Eick, U. (2001). Statistical properties of the rwg(j)
index of agreement. Psychological Methods, 6, 297-310.
Dunlap, W. P., Burke, M. J., & Smith-Crowe, K. (2003). Accurate tests of statistical
significance for rwg and average deviation interrater agreement indices. Journal of
Applied Psychology, 88, 356-362.
James, L.R., Demaree, R.G., & Wolf, G. (1984). Estimating within-group
interrater reliability with and without response bias. Journal of Applied
Psychology, 69, 85-98.
See Also
ad.mrwg.jrwgrwg.j.simrgr.agree
Examples
#An example from Dunlap et al. (2003). The estimate from Dunlap
#et al. Table 2 is 0.53 (p=.05)
RWG.OUT<-rwg.sim(gsize=10,nresp=5,nrep=1000)
summary(RWG.OUT)
quantile(RWG.OUT, c(.95,.99))