Hello, I have just started to work on a path analysis (see attached image for the diagram), but I have encountered an error message.
This is the code I have used: cov_matrix<-var(xdata) library(sem) model.xdata<-specifyModel() x1 -> y2, xy12, NA x2 -> y1, xy21, NA y1 -> y2, yy12, NA y2 -> y3, yy23, NA y2 -> y4, yy24, NA y3 -> y4, yy34, NA y2 <-> y2, y2error, NA y1 <-> y1, y1error, NA y3 <-> y3, y3error, NA y4 <-> y4, y4error, NA model.xdata.sem <- sem(model.xdata, cov_matrix, nrow(xdata)) and the error message is: Error in csem(model = model.description, start, opt.flag = 1, typsize = typsize, : The matrix is non-invertable. I fear to have a problem in the data. I would be very grateful if you could help me to solve this problem and proceed with my analyses. thank you in advance for your help! Sarah [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.