<P> Factor analysis can be used for summarizing high - density oligonucleotide DNA microarrays data at probe level for Affymetrix GeneChips . In this case, the latent variable corresponds to the RNA concentration in a sample . </P> <P> Factor analysis has been implemented in several statistical analysis programs since the 1980s: </P> <Ul> <Li> BMDP </Li> <Li> JMP (statistical software) </Li> <Li> Python: module Scikit - learn </Li> <Li> R (with the base function factanal or fa function in package psych). Rotations are implemented in the GPArotation R package . </Li> <Li> SAS (using PROC FACTOR or PROC CALIS) </Li> <Li> SPSS </Li> <Li> Stata </Li> </Ul> <Li> JMP (statistical software) </Li>

What is the last step in factor analysis