[R] Testing for a second order factor using SEM package

Hi! The following model specification works when testing for first order factors, but when I attempt to test for a second order factor by adding the last 4 lines in the model, I get the error message below: model.cfa.ru - specifyModel() sRU1 - sRU, NA, 1 sRU2 - sRU, lam12 sRU3 - sRU, lam13 sRU4

[R] Fixing error variance in a path analysis to model measurement error in scales using sem package

Hi! I want to construct a path analysis model that can account for measurement error in totally aggregated parcels, which refer to parcels where all of the items in a scale are summed or averaged. If I am not mistaken, Bollen (1989) advocates the following formula for computing the error variance

[R] Logistic regression using package sem

Hi! I constructed a model where most of the variables are linearly related to each other. However, the dependent variable is dichotomous, which means I should not try to fit a linear relationship between the other variables, which are continuos, and this variable. I'm wondering how I would have

[R] Could not compute QR decomposition of Hessian.

Hi, I created the model below, which returns me the following warning message: In sem.default(ram = ram, S = S, N = N, param.names = pars, var.names = vars, : Could not compute QR decomposition of Hessian. Optimization probably did not converge. # Model mDPDF =