VSS.scree function

Plot the successive eigen values for a scree test

Cattell's scree test is one of most simple ways of testing the number of components or factors in a correlation matrix. Here we plot the eigen values of a correlation matrix as well as the eigen values of a factor analysis.

scree(rx,factors=TRUE,pc=TRUE,main="Scree plot",hline=NULL,add=FALSE,sqrt=FALSE) 
VSS.scree(rx, main = "scree plot",sqrt=FALSE)

Details

Among the many ways to choose the optimal number of factors is the scree test. A better function to show the scree as well as compare it to randomly parallel solutions is found found in fa.parallel

Following a suggestion from Marco Del Giudice, I added the sqrt option for version 2.2.12. -

Arguments

• rx: a correlation matrix or a data matrix. If data, then correlations are found using pairwise deletions.
• factors: If true, draw the scree for factors
• pc: If true, draw the scree for components
• hline: if null, draw a horizontal line at 1, otherwise draw it at hline (make negative to not draw it)
• main: Title
• add: Should multiple plots be drawn?
• sqrt: If TRUE, take the sqrt of the eigen value before plotting

References

https://personality-project.org/r/vss.html

Author(s)

William Revelle

See Also

fa.parallel VSS.plot, ICLUST, omega

Examples

scree(attitude)
#VSS.scree(cor(attitude)