covariance structure Factor Analytic covariance structure Alejandra Gonzalez-Beltran Orlaith Burke Camille Maumet FA(q) Philippe Rocca-Serra Tom Nichols adapted from: Heterogeneous Variance: Covariance Structures for Repeated Measures Russell D. Wolfinger. Journal of Agricultural, Biological, and Environmental Statistics Vol. 1, No. 2 (Jun., 1996), pp. 205-230. https://doi.org/10.2307/1400366 and http://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#statug_mixed_sect019.htm Jennrich and Schluchter 1986 factor-analytic structure is a type of heterogeneous covariance structure which is specified for q factors metadata complete