I have a very interesting question...I am currently trying to run a Multivariate Multiple Regression model (i.e. each trial has more than one dependent variable) and the type of independent variables that I am using in this model are dummy variables. Now my question is why does the square of the design matrix (i.e. the Z'Z matrix) become non- invertable if an entire column of the design matrix (i.e. Z matrix)is either all ones or all zero's. That is, why does Z'Z become singular if your entrie sample population has the same answer for any given dummy variable. Thanks Sent via Deja.com http://www.deja.com/ ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================
