Figure 3.
A. Illustration of the second order factor model. The seven subordinated factors (η1, ...,η7) reflect the susceptibilities of the seven ROIs. λ represents the factor loadings of susceptibilities of left and right hemispheres on to the latent variable η, and ε is the residual error term of each manifest indicator (eg. Cdl). ξ is the second order latent variable reflecting total iron concentration across the subcortical nuclei. Γ denotes the regression coefficient between the second ordered latent variable ξ and the subordinated factors η1, ...,η7. Means and intercepts are omitted for parsimony.
B. Hierarchical factor model with three additional covariates; age, curvilinear age and menopause. This is done to predict total subcortical susceptibilities, adding the regression coefficients β1, β2, and β3. Means and intercepts are omitted for parsimony.