understanding I() in lmer formula
On 17-06-14 11:41 AM, Dan Brooks wrote:
Related to your second question about ||, I believe || is shorthand for uncorrelating the slope and intercept, e.g: fm3 <- lmer(Reaction~Days+(Days+0|Subject)+(1|Subject),data=sleepstudy) fm4 <- lmer(Reaction~Days+(1+Days||Subject),data=sleepstudy) As opposed to: fm2 <- lmer(Reaction~Days+(Days+1|Subject),data=sleepstudy) or simply: fm1 <- lmer(Reaction~Days+(Days|Subject),data=sleepstudy) Although happy to be corrected by Ben Bolker if there's more complex examples where this isn't quite right. Best- Dan
That's exactly right. Note that || does *not* work as expected/as one might want it to when one or more of the terms to the left of the bars is a factor. cheers Ben Bolker
On Tue, Jun 13, 2017 at 4:42 PM, Andrew Robinson <mensurationist at gmail.com> wrote:
Don, can you provide a minimal executable example? Cheers, Andrew On 14 Jun 2017, 6:15 AM +1000, peter dalgaard <pdalgd at gmail.com>, wrote:
Not that I really have a clue, but what is that "~" doing in the error
message??
-pd
On 13 Jun 2017, at 21:20 , Don Cohen <don-r-help at isis.cs3-inc.com>
wrote:
Bert Gunter suggested posting this here: Is there a difference between I(x*y) and I(y*x) ? I have a call to lmer that results in this complaint: Error in is.alpha2.subordinate * ~z.min.co.res : non-numeric argument to binary operator when I change this line: I(is.alpha2.subordinate*z.min.co.res)+ to this: I(z.min.co.res*is.alpha2.subordinate)+ the complaint goes away. I'd like to understand why.
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-- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
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