[R] R council with regard to the analysis needd

Julia Edeleva psychexpert1992 at gmail.com
Sat Jul 9 18:12:22 CEST 2016


Dear R community,

I am a PhD student at the University of Münster writing my thesis in
psycholinguistics.

I am currently running statistical analysis on a dataset with 3 fixed
factors (syntax, position), each with 2 levels and their interaction
(syntax*position). The accuracy rate is the dependent variable.

I first created a general linear mixed effects model (lme4), including both
the factors and their interaction and requested its summary.

 *M1 = glmer (correctness ~ syntax+position + syntax*position +(1|subj_nr)
+ (1|item_sf), data = df.rus2, family = binomial) *

I now want to test the contribution of the factors to the power of the
model, taken separately, by creating further models with individual factors
dropped and comparing the models to the baseline model.

My question is: should I drop the factors from the original model?

e.g. for the effect of syntax

*M2 = glmer (correctness ~ syntax + syntax*position +(1|subj_nr) +
(1|item_sf), data = df.rus2, family = binomial) *

Or should I test the main effects separately from the interaction?

The baseline model:

*M0 = glmer (correctness ~ syntax + position +(1|subj_nr) + (1|item_sf),
data = df.rus2, family = binomial)*

Models for comparison:

*M1 = glmer (correctness ~ syntax  +(1|subj_nr) + (1|item_sf), data =
df.rus2, family = binomial)*


*M2 = glmer (correctness ~ position +(1|subj_nr) + (1|item_sf), data =
df.rus2, family = binomial)*


*M3 = glmer (correctness ~ syntax * position +(1|subj_nr) + (1|item_sf),
data = df.rus2, family = binomial)*


Thank you in advance.
Sincerely
Julia Edeleva

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