Dear all I' m running a model with proc glm to fit a multiple regression. Y = score 's questionnaire (to measure quality of life) X1 = treatment (value a, b, c) X2= age (continuos) X3= education (low and high) X4= gendere (Male, Female) X5=BMI (continuos) There's no multicollinearity between covariates The code is: proc glm data=mydataset; class X1 X3 X4; model Y= X1 X2 X3 X4 X5 /solution; run; In the output tables with parameter estimate there's a footnote: The X'X matrix has been found to be singular, and a generalized inverse was used to solve the normal equations. Terms whose estimates are followed by the letter 'B' are not uniquely estimable. What's the meaning? The results validity are questionable? Is it recommend to run a different model? What kind of model? Thanks in advance
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