| SSpower {semTools} | R Documentation |
Determines power for model parameters using the Satorra & Sarris (1985) method
SSpower(popModel, n, powerModel, fun = "cfa", nparam = 1, alpha = .05, ...)
popModel |
lavaan syntax for the population model. This model should specify population values for all paramters in the model. |
n |
Sample size used in power calculation |
powerModel |
lavaan syntax for the model to be analyzed. This syntax should have the parameter(s) of interest fixed to 0 (or some other number). |
fun |
The character of the function name used in running lavaan model ( |
nparam |
The number of parameters one is constrained in |
alpha |
The Type I error rate used to assess power |
... |
Other arguments to be passed to the specified lavaan function ( |
Alexander M. Schoemann (East Carolina University; schoemanna@ecu.edu)
Satorra, A., & Saris, W. E. (1985). Power of the likelihood ratio test in covariance structure analysis. Psychometrika, 50, 83-90.
library(lavaan)
#Specify population values. Note every paramter has a fixed value
modelP <- '
f1 =~ .7*V1 + .7*V2 + .7*V3 + .7*V4
f2 =~ .7*V5 + .7*V6 + .7*V7 + .7*V8
f1 ~~ .3*f2
f1 ~~ 1*f1
f2 ~~ 1*f2
V1 ~~ .51*V1
V2 ~~ .51*V2
V3 ~~ .51*V3
V4 ~~ .51*V4
V5 ~~ .51*V5
V6 ~~ .51*V6
V7 ~~ .51*V7
V8 ~~ .51*V8
'
#Specify model to be analyzed. Note parameter of interest f1~~f2 is fixed to 0.
modelA <- '
f1 =~ V1 + V2 + V3 + V4
f2 =~ V5 + V6 + V7 + V8
f1 ~~ 0*f2
'
SSpower(modelP, 150, modelA, std.lv=TRUE)
##Get power for a range of values
Ns <- seq(100, 500, 40)
powVals <- rep(NA, length(Ns))
for(i in 1:length(Ns)){
powVals[i] <- SSpower(modelP, Ns[i], modelA)
}
plot(Ns, powVals, type = 'l')