Hi, I want to test for independence in my GLS model fitp2, but when I try to use the dwtest function in the lmtest library, I get the error message "Error in terms.default(formula) : no terms component". The model and data set are below. Any suggestions would be really helpful! Thanks a lot in advance, M. Grace fitp2: fitp2<-gls(V3_total~D_total+P_total,data=pdata,weights=varPower()) based on the data set pdata: pdata D_total V3_total P_total 1 75 158000 302.033 2 221 258000 126.664 3 1050 280000 538.547 4 8100 208000 1090.068 5 22100 235000 2038.937 6 5300 570000 2626.226 7 3250 454000 2326.473 8 6540 169000 5613.525 9 5248 247000 6011.532 10 22484 542000 15140.006 11 30841 530000 13324.048 12 7480 497000 10481.812 13 2664 467000 5776.274 14 432 285000 1849.763 ------------------------------------------------------------------ University of St Andrews Webmail: https://webmail.st-andrews.ac.uk