So what are mixed effects models and how do they relate to GEE models?  Well, they are called mixed effects models because they contain both fixed effects and random effects.  And we pretty much know what’s going on with fixed effects but not so much with random effects, as discussed before.  Like if you are giving a treatment to patients over time, you most likely know what the treatment is (I would hope!) so that’s your fixed effect, while you random effects are something you may not be able to know or predict exactly, as we talked about before.  Like we may not know how each patient reacts to treatment so patient would be a random effect.  Or like the time I went to see my husband Joe Manganiello at the Old Orchard Barnes & Nobel and attended his Q&A session and was planning to get his book and go to his book signing and maybe slip him my book in the process if I had not a prior commitment.  Or that and I was chicken sh … so in this instance, since I knew the time and place where he would appear, time and place would be a fixed effect.  On the other hand, just the other day, I was rushing between my two offices and ran into Bill and Guiliana Rancic with their little son.  Now, in that case, time and place would still be fixed effect since I still knew where I was (Streeterville) and when I was there (early Thursday afternoon) so those would still be fixed effects but I didn’t know that I would run into them, so that would be a random effect.  Actually, I liked the latter encounter better (apologies to my future husband, Joe), maybe because the element of randomness made it feel more natural.  Like I just talked to them and interacted with their little boy as I would with any other couple with a small child.  Was nice.  But anywhoo, I don’t have a picture or anything of my meeting with them as I was rushing to my office and I did not have my book(s) on hand to give them (drats!) but it was still pretty cool to see them.  I do have a picture of  Joe Manganiello and a picture of his book under my Christmas tree though, for what it’s worth.

jm_in_bn

Just no autograph in the book from him inside since I was chicken sh …oot, now why I did leave early?  Ah well, next time like at the Order of The Dimensions movie premiere … or like on our wedding night, of course.  Anyway, until next time … still working on a topic but hope to make it good … and Order of The Dimensions-related, of course!

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