I am trying to simulate a dataset using Parallel Latent CTT model and this is what i have done so far: (START) #Importing psych library for all the simulation related functions library(psych) # Settting the working directory path to C:/NCME path="C:/NCME" setwd(path) #Using the function to generate the data GenData <- congeneric.sim(N=500, loads = c(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), short = FALSE) #Rounding upto 2 decimal places while showing the correlation matrix round(cor(GenData$observed),2) #Factor Score FactorScore=factor.pa(GenData$observed,1,scores = "TRUE", rotate="none") round(cor(FactorScore$scores,GenData$latent),2) (END) Please let me know if I am moving into the right direction, if not then, please let me know the correct way to simulate the dataset Thanks in Advance Regards, Nidhi Kohli *************************************** Nidhi Kohli, M.Ed. Doctoral Student Department of Measurement, Statistics and Evaluation University of Maryland 1230 Benjamin Building College Park, MD 20742-1115 e-mail: nidhik at umd.edu
Simulating dataset using Parallel Latent CTT model?
2 messages · Nidhi Kohli, William Revelle
Nidhi, Presumably, you are trying to simulate 20 items all sharing one general factor but having some error. The model as you specified it has no error. Thus all the correlations will be 1 and the factors will not make any sense. Most items have loadings on a general factor of the order of about .4 to .6. You might try: GenData <- congeneric.sim(N=500, loads = rep(.5,20), short = FALSE) Then you will find that the factor scores found by factor.pa correlate at .93 with the latent variable.
FactorScore=factor.pa(GenData$observed,1,scores = "TRUE", rotate="none") round(cor(FactorScore$scores,GenData$latent),2)
Bill
At 8:27 AM -0500 12/26/08, Nidhi Kohli wrote:
I am trying to simulate a dataset using Parallel Latent CTT model and this is what i have done so far: (START) #Importing psych library for all the simulation related functions library(psych) # Settting the working directory path to C:/NCME path="C:/NCME" setwd(path) #Using the function to generate the data GenData <- congeneric.sim(N=500, loads = c(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), short = FALSE) #Rounding upto 2 decimal places while showing the correlation matrix round(cor(GenData$observed),2) #Factor Score FactorScore=factor.pa(GenData$observed,1,scores = "TRUE", rotate="none") round(cor(FactorScore$scores,GenData$latent),2) (END) Please let me know if I am moving into the right direction, if not then, please let me know the correct way to simulate the dataset Thanks in Advance Regards, Nidhi Kohli *************************************** Nidhi Kohli, M.Ed. Doctoral Student Department of Measurement, Statistics and Evaluation University of Maryland 1230 Benjamin Building College Park, MD 20742-1115 e-mail: nidhik at umd.edu
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William Revelle http://personality-project.org/revelle.html Professor http://personality-project.org/personality.html Department of Psychology http://www.wcas.northwestern.edu/psych/ Northwestern University http://www.northwestern.edu/ Attend ISSID/ARP:2009 http://issid.org/issid.2009/