Figure 1
From: Factor-analytic models for genotype × environment type problems and structured covariance matrices
Fill pattern of coefficient matrix in the mixed model equations for 'toy example' comprising four countries with one global sire used in all countries, one local sire in each country and two offspring per sire; (a) standard multivariate, (b) principal component model fitting all four factors, and (c) extended factor-analytic model fitting one common factor. (Non-zero elements arising from data part (red square) and from inverse of relationship matrix (blue square))