Including all treatments in crossover design mixed model in SAS

ph6 — Sun, 10 May 2020 15:17:34 GMT

Hi, I have a dataset effects of 3 treatments against ctrl on cell-lines collected from 4 donors.

```
Treatment donor value log_val
Ctrl D1 xx
T1 D2 xx
T2 D3 xx
T4 D4 xx
```
I would like to compare the effects of treatments against ctrl and also with each other using a mixed model. I use the following mixed model in SAS:
```
PROC MIXED data=data;
CLASS DONOR TREATMENT;
MODEL log_val= TREATMENT/ DDFM=SATTERTH;
random DONOR ;
LSMEANS TREATMENT / PDIFF CL E;
estimate 'T/R' TREATMENT -1 1 / cl ;
run;
```

When I include all the treatments in one model I am getting higher standard errors than the case if I include only two treatments which I want to compare for different combinations of treatments. Which approach should I choose? Including all the treatments as once or including two treatments and repeating for different combinations?

Re: Including all treatments in crossover design mixed model in SAS

blueskyxyz — Mon, 01 Mar 2021 09:18:32 GMT

adjust your model

1. add visit information if the dataset has it, like week information

2. include week in part of repeated statement

3.treat week, treatment and treatment-week interaction, baseline of val... as fixed effects

4. use cs, ar or un matrix to converge

.....

topic Including all treatments in crossover design mixed model in SAS in SAS Programming

Including all treatments in crossover design mixed model in SAS

Re: Including all treatments in crossover design mixed model in SAS