& Strimmer 2005) of the covariance matrix. R packages e1071 (for missing data imputation), corpcor (for covariance shrinkage), nFACTOR and factanal were used for the purposes of factor analysis. Factor loadings were analyzed to obtain factor interpretations. Factor scores were obtained for all interpreted latent factors. Quantitative trait locus mapping was performed on these latent factors to identify common genetic drivers of variability in factor scores.
