\name{Schmid}
\Rdversion{1.1}
\alias{Schmid}
\alias{schmid.leiman}
\alias{West}
\alias{Chen}
\docType{data}
\title{12 variables created by Schmid and Leiman to show the Schmid-Leiman Transformation}

\description{
John Schmid and John M. Leiman (1957) discuss how to transform a hierarchical factor structure to a bifactor structure. Schmid contains the example 12 x 12 correlation matrix. schmid.leiman is a 12 x 12 correlation matrix with communalities on the diagonal. This can be used to show the effect of correcting for attenuation. Two additional data sets are taken from Chen et al. (2006).
}
\usage{data(Schmid)}

\details{ Two artificial correlation matrices from Schmid and Leiman (1957). One real and one artificial covariance matrices from Chen et al. (2006). 
\itemize{
\item Schmid: a 12 x 12 artificial correlation matrix created to show the Schmid-Leiman transformation. 
\item schmid.leiman: A 12 x 12 matrix with communalities on the diagonal.  Treating this as a covariance matrix shows the 6 x 6 factor solution
\item Chen: An 18 x 18 covariance matrix of health related quality of life items from Chen et al. (2006). Number of observations = 403.  The first item is a measure of the quality of life.  The remaining 17 items form four subfactors: The items are (a) Cognition subscale: ``Have difficulty reasoning
and solving problems?"  ``React slowly to things that were said or done?"; ``Become confused and start several actions at a time?"  ``Forget where you
put things or appointments?"; ``Have difficulty concentrating?"  (b) Vitality
subscale: ``Feel tired?"  ``Have enough energy to do the things you want?" (R) 
``Feel worn out?" ; ``Feel full of pep?" (R). (c) Mental health subscale: ``Feel
calm and peaceful?"(R)  ``Feel downhearted and blue?"; ``Feel very
happy"(R) ; ``Feel very nervous?" ; ``Feel so down in the dumps nothing could
cheer you up?  (d) Disease worry subscale: ``Were you afraid because of your health?"; ``Were you frustrated about your health?"; ``Was your health a worry in your life?" .
\item West: A 16 x 16 artificial covariance matrix from Chen et al. (2006).
}
}
\source{
John Schmid Jr. and John. M. Leiman (1957), The development of hierarchical factor solutions.Psychometrika, 22, 83-90.

F.F. Chen, S.G. West, and K.H. Sousa.(2006) A comparison of bifactor and second-order models of quality of life. Multivariate Behavioral Research, 41(2):189-225, 2006.

}
\references{

Y.-F. Yung, D.Thissen, and L.D. McLeod. (1999) On the relationship between the higher-order factor model and the hierarchical factor model. Psychometrika, 64(2):113-128, 1999.



}
\examples{
data(Schmid)
cor.plot(Schmid,TRUE)
print(fa(Schmid,6,rotate="oblimin"),cut=0)  #shows an oblique solution
round(cov2cor(schmid.leiman),2)
cor.plot(cov2cor(West),TRUE)
}
\keyword{datasets}