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Dec 5, 2023 at 9:40 vote accept Harmony
Dec 4, 2023 at 0:54 history edited statmerkur CC BY-SA 4.0
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Dec 3, 2023 at 19:22 answer added Dimitris Rizopoulos timeline score: 7
Dec 3, 2023 at 18:49 comment added PBulls I've seen conflicting information but always assumed lme4 did unstructured only. This page shows how you can trick it into fitting certain structured covariances - never tried though & looks complicated.
Dec 3, 2023 at 16:53 comment added Harmony @PeterFlom I have also read that by fitting random slopes for the time variable, this results in something similar to an AR1 structure. I have probably got that wrong (AR1 that is), I'm not entirely sure what exactly it does do (that was going to be the subject of a further question. I just didn't want to ask too much in one go!)
Dec 3, 2023 at 13:21 comment added Peter Flom @statmerkur That makes sense and is good to know. I've retired, but when I was working, I mostly used SAS. These days, I don't have access to it (it's expensive) and my R knowledge is somewhat lacking.
Dec 3, 2023 at 13:09 comment added statmerkur @PeterFlom This is a limitation of the lme4 package, not of $\textsf{R}$. Other package, such as nlme, implement R-side effects or covariance structures.
Dec 3, 2023 at 11:36 comment added Peter Flom This seems like a major disadvantage of R compared to SAS, which offers a large variety of choices. But I wonder if there is a work around.
Dec 3, 2023 at 11:14 answer added statmerkur timeline score: 5
Dec 3, 2023 at 10:42 history edited Harmony
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S Dec 2, 2023 at 21:01 review First questions
Dec 2, 2023 at 22:15
S Dec 2, 2023 at 21:01 history asked Harmony CC BY-SA 4.0