Timeline for Assessing the need for multi level model
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 5, 2018 at 17:04 | comment | added | Björn | In my experience there usually is. | |
| Sep 5, 2018 at 16:58 | comment | added | DiscoR | @Björn I see, thanks, I am using R for this analysis. I will re arrange my data. I am wondering if I am already using a model with random intercepts and random slopes, is there still value in using baseline as fixed effect? | |
| Sep 5, 2018 at 16:48 | comment | added | Björn | In SAS you would have separate records for each post baseline visit with a variable for the baseline and then proc mixed; class avisit treatment subject; model aval = treatment avisit base treatmentavisit avisitbase / ddfm=kr; repeated avisit / subject=subject type=un;run; | |
| Sep 5, 2018 at 16:39 | comment | added | DiscoR | @Björn I am trying to run the analysis you suggested. However I am not sure how to use only post baseline values as outcome (outcome at time 6 weeks and 12 weeks). What would the mixed effect code look like for this? | |
| Sep 4, 2018 at 21:28 | vote | accept | DiscoR | ||
| Sep 4, 2018 at 16:14 | comment | added | DiscoR | @Bjorn I see. The model you are describing is that a ANCOVA where baseline measures are used as a fixed effect? Can this be carried out within lme? | |
| Sep 4, 2018 at 6:57 | answer | added | Dimitris Rizopoulos | timeline score: 3 | |
| Sep 4, 2018 at 6:47 | comment | added | Björn | Building your model in such a stepwise fashion will invalidate p-values, confidence intervals etc. from the final model. Why not prespecify the standard MMRM for this type of situation? I.e. Change or value at each post baseline visit = treatment + visit + baseline + visit*treatment + visit *baseline with an unstructured (simplifies to just a random effect + allowing for different variance at each visit when you just have two part baseline visits) covariance matrix describing the correlation of visits within a patient? | |
| Sep 4, 2018 at 0:12 | comment | added | Peter Flom | In your code, you have the same model 3 times and you don't have all teh models that are in your output, so something is wrong there. | |
| Sep 3, 2018 at 22:51 | history | asked | DiscoR | CC BY-SA 4.0 |