[R-sig-ME] What p value should I report here?

Ben Bolker bbo|ker @end|ng |rom gm@||@com
Fri May 3 04:53:24 CEST 2019


  What we'd like to see is the *results* of summary(Vert_effect) and
summary(model.frame(glmm_Vert_effect)) ... for example, if I was running
the first example in ?lmer, the desired output would look something like
this (here, the two outputs are identical because there are no NA values
in the input).


> library(lme4)
Loading required package: Matrix
> fm1 <- lmer(Reaction~Days+(1|Subject), sleepstudy)
> summary(sleepstudy)
    Reaction          Days        Subject
 Min.   :194.3   Min.   :0.0   308    : 10
 1st Qu.:255.4   1st Qu.:2.0   309    : 10
 Median :288.7   Median :4.5   310    : 10
 Mean   :298.5   Mean   :4.5   330    : 10
 3rd Qu.:336.8   3rd Qu.:7.0   331    : 10
 Max.   :466.4   Max.   :9.0   332    : 10
                               (Other):120
> summary(model.frame(fm1))
    Reaction          Days        Subject
 Min.   :194.3   Min.   :0.0   308    : 10
 1st Qu.:255.4   1st Qu.:2.0   309    : 10
 Median :288.7   Median :4.5   310    : 10
 Mean   :298.5   Mean   :4.5   330    : 10
 3rd Qu.:336.8   3rd Qu.:7.0   331    : 10
 Max.   :466.4   Max.   :9.0   332    : 10
                               (Other):120


On 2019-05-02 10:51 p.m., DESPINA MICHAILIDOU wrote:
> The code is
> 
> glmm_Vert_effect <- glmer(Vert_effect ~ P-Diz-today + (1|
> ID/SCAN_DATE/Side), data=GCA_data, family=binomial(link= "logit"))
> 
> summary(Vert_effect).
> 
> 
> That is your question?
> 
> 
> I am sorry i am very new to R.
> 
> 
> Thank you for your interest and help. Really appreciate it.
> 
> 
> Despina
> 
> 
> Στις Πέμ, 2 Μαΐ 2019 στις 10:40 μ.μ., ο/η Ben Bolker <bbolker using gmail.com
> <mailto:bbolker using gmail.com>> έγραψε:
> 
> 
>       We will be able to help much better if you can provide a reproducible
>     example, or at least the results of the summary() commands requested
>     below ...
> 
>     On 2019-05-02 10:29 p.m., DESPINA MICHAILIDOU wrote:
>     > Yes you are correct. I have a 0 or 1 scoring outcome. I do have some
>     > blanks in my observations.  Thank you for your response.
>     >
>     > Despina
>     >
>     > Στις Πέμ, 2 Μαΐ 2019 στις 10:19 μ.μ., ο/η Ben Bolker
>     <bbolker using gmail.com <mailto:bbolker using gmail.com>
>     > <mailto:bbolker using gmail.com <mailto:bbolker using gmail.com>>> έγραψε:
>     >
>     >
>     >       Can you show us summary(GCA_data) and
>     >     summary(model.frame(fitted_model)) please? It looks like for
>     some reason
>     >     (maybe because of observations dropped due to NA values?) you
>     have no
>     >     variation in your predictor variable (P_Diz_today).
>     >
>     >       It's also potentially problematic that you have an
>     observation-level
>     >     random effect for a Bernoulli outcome (i.e., you're fitting a
>     binomial
>     >     model with a single-column value as the response and no weights=
>     >     argument, which implies you have a 0/1 outcome; you have the
>     same number
>     >     of groups in your fully nested [ID:Scan:Side] random effect as
>     >     observations), but I don't think this would lead to the
>     dropping of the
>     >     P_Diz_today predictor ...
>     >
>     >       cheers
>     >         Ben Bolker
>     >
>     >     On 2019-05-02 3:30 p.m., DESPINA MICHAILIDOU wrote:
>     >     > Hi everyone,
>     >     >
>     >     >
>     >     > I am running this regression analysis model and I get the
>     >     following output.
>     >     > What P value should I report for my variable P-Dizz today?What
>     >     does it mean
>     >     > that fixed-effect model matrix is rank deficient so dropping 1
>     >     column /
>     >     > coefficient? Can anyone help me with the interpretation of
>     those data?
>     >     >
>     >     >
>     >     > Thank you in advance.
>     >     >
>     >     >
>     >     > Despina
>     >     >
>     >     >
>     >     > Generalized linear mixed model fit by maximum likelihood
>     (Laplace
>     >     > Approximation) ['glmerMod']
>     >     >
>     >     >  Family: binomial  ( logit )
>     >     >
>     >     > Formula: Vert_effect ~ P_Diz_today + (1 | ID/SCAN_DATE/Side)
>     >     >
>     >     >    Data: GCA_data
>     >     >
>     >     >
>     >     >
>     >     >      AIC      BIC   logLik deviance df.resid
>     >     >
>     >     >     80.3     94.5    -36.1     72.3      254
>     >     >
>     >     >
>     >     >
>     >     > Scaled residuals:
>     >     >
>     >     >       Min        1Q    Median        3Q       Max
>     >     >
>     >     > -0.012501 -0.000639 -0.000639 -0.000639  0.105723
>     >     >
>     >     >
>     >     >
>     >     > Random effects:
>     >     >
>     >     >  Groups              Name        Variance Std.Dev.
>     >     >
>     >     >  Side:(SCAN_DATE:ID) (Intercept) 1502.7   38.76
>     >     >
>     >     >  SCAN_DATE:ID        (Intercept)    0.0    0.00
>     >     >
>     >     >  ID                  (Intercept)  235.1   15.33
>     >     >
>     >     > Number of obs: 258, groups:  Side:(SCAN_DATE:ID), 258;
>     >     SCAN_DATE:ID, 130;
>     >     > ID, 52
>     >     >
>     >     >
>     >     >
>     >     > Fixed effects:
>     >     >
>     >     >             Estimate Std. Error z value Pr(>|z|)
>     >     >
>     >     > (Intercept)  -14.711      3.646  -4.035 5.47e-05 ***
>     >     >
>     >     > ---
>     >     >
>     >     > Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>     >     >
>     >     > fit warnings:
>     >     >
>     >     > fixed-effect model matrix is rank deficient so dropping 1
>     column /
>     >     > coefficient
>     >     >
>     >     > convergence code: 0
>     >     >
>     >     > boundary (singular) fit: see ?isSingular
>     >     >
>     >     >       [[alternative HTML version deleted]]
>     >     >
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