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lme4 and nlme are R packages used for fitting linear, generalized linear and nonlinear mixed effects models. For general questions about mixed models use [mixed-model] tag.
1
vote
1
answer
467
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Effect size for fixed effect variable with >2 levels binomial glmm (lme4)
In the output from summary(model) I get estimates for each of the fixed effects. … of a categorical variable with >2 levels (the equivalent to Cohen's d when conducting a normal ANOVA). …
7
votes
3
answers
463
views
If the categorical variable is retained in my final model in R, then why does the post hoc a...
lmm.1 5 -219.80 -204.71 114.90 -229.80 9.3806 2 0.009184 **
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1`
`
I had forgotten to include my model's summary … in my my question, so here it is:
> summary(lmm.1)
Linear mixed model fit by REML ['lmerMod']
Formula: condition ~ category.of.urbanization + (1 | river)
Data: fish
REML criterion at convergence: -214.3 …
0
votes
1
answer
1k
views
lme for multiple groups comparing treatment vs control
> lm <- lme(weight~time*cond, random=~time|miRs, data=testDose)
> anova(lm)
numDF denDF F-value p-value
(Intercept) 1 38 233748.85 <.0001
time 1 38 398.12 <.0001 … cond 3 38 7.14 0.0006
time:cond 3 38 2.34 0.0887
> summary(lm)
Linear mixed-effects model fit by REML
Data: testDose
AIC BIC logLik
51.94759 72.21414 …
2
votes
2
answers
976
views
Fixed effect turns insignificant when including random effect - Multilevel
estimate a model with only a fixed effect of my predictor, as such:
fit1 <- lme(fixed = stress ~ 1 + predictor_centred + predictor_mean, random = ~ 1 |ID, data = data, method = "REML", na.action=na.exclude)
summary … fit2 <- lme(fixed = stress ~ 1 + predictor_centred + predictor_mean, random = ~ 1 + predictor_centred|ID, data = data, method = "REML", na.action=na.exclude)
anova(fit1, fit2)
Model df AIC …
7
votes
If the categorical variable is retained in my final model in R, then why does the post hoc a...
See:
Can ANOVA be significant when none of the pairwise t-tests is?
Discrepancy between the results of the ANOVA and the post-hoc test: How should be such results interpreted and presented? … d,d,
-d,d,
-d,d)
x = as.factor(c(0,0,1,1,2,2))
mm = lm(y~x)
### LR test 0.01058
lmtest::lrtest(mm)
### ANOVA test 0.103
mod = aov(mm)
summary(mod)
### Tukey test 0.128822
TukeyHSD(mod) …
3
votes
1
answer
1k
views
Generalized linear mixed effects in repeated measures analysis
When I use car::Anova , there is no time * group interaction. Is it wrong to do the following analysis? What's the difference between them? … Anova(model, type = 3)
Response: score
Chisq Df Pr(>Chisq)
(Intercept) 13.9981 1 0.000183 ***
time 83.3778 5 < 2.2e-16 ***
group 0.6852 1 0.407803
time:group …
2
votes
1
answer
81
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R lmer help understanding my mixed model output
tbl", "data.frame"))
EDIT2: Updated model and output
mixed.lmer.all <- lmer(Intertegular.Width ~
Urban.Intensity*Sociality*Nesting + Urban.Intensity*Diet +
Genus + Sex + (1|SiteID), data=df)
summary … (mixed.lmer.all); Anova(mixed.lmer.all)
Output:
REML criterion at convergence: 2893.8
Scaled residuals:
Min 1Q Median 3Q Max
-8.8063 -0.5070 0.0109 0.5188 7.0897
Random effects …
2
votes
2
answers
250
views
Mixed Effects models approach?
mod <- glmer(value~xval+(0+xval|zone),family=gaussian(link="log"),data = dat)
#Null model
mod0 <- glmer(value~(0+xval|zone),family=gaussian(link="log"),data = dat);
anova(mod,mod0)
summary(mod)
# dispersion … and interrogation
summary(mod)
anova(mod)
lme4::VarCorr(mod)
car::Anova(mod)
Based on the diagnostics the models look good right? …
0
votes
1
answer
60
views
lmer - how to report results and group differences? [closed]
0.0996 2 0.951421
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
I settle on m7, and proceed to fit the model:
model <- lmer(Score ~ 1 + Groups*Time + (1 | ID), data = df)
summary … I also pull the ANOVA table for this model:
anova(model)
Type III Analysis of Variance Table with Satterthwaite's method
Sum Sq Mean Sq NumDF DenDF F value Pr(>F)
Groups 122.848 …
3
votes
1
answer
222
views
lme4 Inconsistency
(Model1,type=3)
summary(Model1)
Results:
Factor Pr(>F)
Group 7.643e-05
Diff 1.274e-09
Group:Diff 3.346e-16
Model2 <- lmer(RT~Group*Diff + (1|Item) + (1|Subject),data=data, lmerControl(optimizer = "bobyqa … "), REML=F, na.action=na.omit)
anova(Model2,type=3)
summary(Model2)
Results:
Factor Pr(>F)
Group 8.300e-05
Diff 1.350e-09
Group:Diff 5.308e-06
As you can see, the two models produce different results …
1
vote
Accepted
Model comparison or beta coefficient of full model?
library(lmerTest)
fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)
fm0 <- update(fm1, . ~ . - Days)
coef(summary(fm1))["Days", "Pr(>|t|)"] ## 3.623824e-06
coef(summary(fm1, ddf = "Kenward-Roger … "))["Days", "Pr(>|t|)"] ## 3.263808e-06
anova(fm1, fm0) ## p-value: 1.226e-06
pbkrtest::KRmodcomp(fm1, fm0) ## 3.263808e-06
The odd one out here is anova(), which does a likelihood ratio test (i.e. …
1
vote
1
answer
77
views
Describing data structure and specifying a linear mixed model in nlme with nested and crosse...
This is the thought process I have been working through so far:
My first attempt to model the data was:
library(nlme)
m1 <- lme(MR ~ Condition * Run, random = ~1|ID, data = df)
summary(m1)
anova(m1) … (m2)
anova(m2)
Is this a correct model specification and does it capture the effect of Group? …
3
votes
Accepted
Why estimated population variance differs from estimated $\sigma^2 + \tau^2$ in this random ...
(and shown under Random Effects by your summary(empty_model)). … This entails that the "common" variance estimate is downwardly biased, in case the true data are generated by a random-effects Anova model $Y_{ij}=\gamma_{00}+u_{0j}+e_{ij}$. …
12
votes
2
answers
34k
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How to perform post-hoc comparison on interaction term with mixed-effects model?
I'm able to do it for a simple main effect (e.g., Sediment):
summary(glht(mod1,linfct=mcp(Sediment="Tukey")))
But the glht() function doesn't work for interaction terms. … Hydrology)
mod2 <- lme(Variable ~ -1 + SH, data=mydata, random=~1|Site/Hydrology)
summary(glht(mod2, linfct=mcp(SH="Tukey")))
Is it possible to use the same approach in the case of a 3-way anova? …
23
votes
Is this an acceptable way to analyse mixed effect models with lme4 in R?
To get a nice summary of AIC and log-likelihood models, you can use the anova() function, which has been overloaded to accept mer objects. … For looking at the individual effects (i.e. the stuff you would see in a traditional ANOVA), you should look at the $t$-values for the fixed effects in the models (which are part of the summary() if I'm …