[R-sig-ME] lme4 merMod model object

Nathan Pace n.l.pace at utah.edu
Mon Nov 20 06:06:08 CET 2017


Hi John,

Your example was just what I needed.

I can see now that your example is an illustration of this sentence in the documentation:

“Alternatively, the hypothesis can be specified symbolically as a character vector with one or more
elements, each of which gives either a linear combination of coefficients, or a linear equation in the
coefficients (i.e., with both a left and right side separated by an equals sign).”

I must confess to an inability at times to translate words in documentation into code.

So, you sample code was very helpful.


Nathan

On 1811//2017, 7:45 AM, "Fox, John" <jfox at mcmaster.ca> wrote:

    Dear Nathan,
    
    Yes, you should be able to use linearHypothesis() in the car package. The command would be something like
    
    linearHypothesis(your.model, c("coef1 - coef2 = 0",  "coef3 - coef4 = 0"))
    
    You could equivalently specify the hypothesis as c("coef1 - coef2",  "coef3 - coef4"), with the 0s implied, or as c("coef1 = coef2",  "coef3 = coef4 ").
    
    I'm curious why that wasn't clear from ?linearHypothesis.
    
    I hope this helps,
     John
    
    -----------------------------
    John Fox, Professor Emeritus
    McMaster University
    Hamilton, Ontario, Canada
    Web: socialsciences.mcmaster.ca/jfox/
    
    
    
    > -----Original Message-----
    > From: R-sig-mixed-models [mailto:r-sig-mixed-models-bounces at r-project.org]
    > On Behalf Of Nathan Pace
    > Sent: Friday, November 17, 2017 7:02 PM
    > To: R-sig-mixed-models <r-sig-mixed-models at r-project.org>
    > Subject: [R-sig-ME] lme4 merMod model object
    > 
    > Hi mixed model experts,
    > 
    > I have a GLMM (binomial) model estimated in lme4 using glmer.
    > 
    > There are many linear coefficients such as coef1, coef2, coef3, coef4, …
    > 
    > I have used glht from multcomp to test coefficient contrasts such as coef1 –
    > coef2 = 0.
    > 
    > Now I desire to test sets of linear contrasts in the model jointly such as coef1 –
    > coef2 = 0 & coef3 – coef4 = 0.
    > 
    > By my reading, this should be possible in the linearHypothesis function of the
    > car package.
    > 
    > If someone has already used sets of contrast vectors for that purpose, I would
    > appreciate learning of the format.
    > 
    > Thanks,
    > 
    > vd
    > Nathan Pace
    > University of Utah
    > 
    > 
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