using trt , covar as the covariate and dmi as the dependent variable, was homogeneity of slopes

[LABRADOR]

using trt , covar as the covariate and dmi as the dependent variable, was homogeneity of slopes met?

*below is the text file data diet.txt* 

cow trt block covar dmi weeks
747 4 4 22.4757 24.4895 14
755 5 5 24.5157 26.7524 14
819 4 3 22.1100 25.4132 8
835 3 10 18.9529 27.6605 14
849 5 2 20.0657 17.0912 14
850 2 8 21.0600 26.4908 14
852 1 6 23.8933 27.8113 13
855 3 2 27.0329 27.0967 14
869 3 5 25.0800 25.1205 14
872 1 10 21.4414 27.7596 12
890 5 6 24.6457 23.7472 14
894 6 9 23.7971 26.0426 13
1549 4 8 21.8886 25.1794 14
3135 1 9 18.7286 21.4793 14
3164 2 2 19.5083 22.6606 12
3231 5 4 18.5886 23.0251 14
3240 2 7 19.8500 27.5362 14
3353 1 4 . 24.7224 14
3366 5 1 20.1900 24.2389 14
3372 4 9 23.5571 27.1255 14
3408 6 1 20.2600 23.9520 14
3440 1 8 19.2750 26.2302 14
3455 4 5 17.0886 24.9188 14
3460 3 9 20.4257 25.1809 14
3466 2 3 24.6114 28.0106 14
3467 4 1 14.8033 22.9552 14
3471 1 1 16.9200 24.3709 14
3478 6 3 23.4171 22.9222 14
3499 1 2 22.0329 26.2007 14
3508 3 1 27.0543 32.9527 14
3520 6 6 23.3329 27.4932 14
3527 6 4 20.9614 23.8124 14
3528 2 9 18.5557 23.3623 14
3529 5 10 20.4143 25.1781 14
3531 2 1 20.8167 24.6142 14
3542 2 6 25.7871 28.0095 14
3561 2 4 25.6457 26.9496 14
3564 5 9 23.8586 27.8948 14
3580 3 4 22.4071 24.8609 14
3586 4 2 24.5700 24.9605 14
3589 6 7 15.9386 22.3435 14
3593 1 5 21.6429 24.2462 14
3594 3 3 . 24.9867 12
3595 2 5 19.0300 28.0241 14
3596 6 5 27.1671 27.2993 14
3598 6 2 21.5667 25.4685 14
3604 4 10 20.8714 26.6923 14
3605 1 3 19.7671 28.1831 14
3611 3 6 18.5186 23.6910 14
3613 3 8 24.3829 26.6503 14
3615 5 7 22.8329 25.3444 14
3622 4 7 19.0857 22.9824 14
3623 6 10 19.0486 23.3875 14
3624 4 6 21.3286 21.6679 14
3629 3 7 18.5771 18.9699 14
3630 6 8 24.1200 26.3490 7
3643 2 10 17.6314 23.7072 14

  How do I test for homogeneity of slopes in SAS 9.4? 

[StatDave · Accepted solution]

This can be done as described generally in this note and in the example note that it links to. In this case, the test for the trt*covar interaction is a test of the equality of slopes - if significant, that suggests that the slopes differ. If not, then the interaction can be dropped and the covar estimate is the estimated common slope.

proc glm;
class trt;
model dmi=trt covar covar*trt / noint solution;
run; quit;

[LABRADOR]

Thank you!