Chapter 7 -Model

library(tidyverse)

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library(lme4)

## Loading required package: Matrix
## 
## Attaching package: 'Matrix'
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## The following objects are masked from 'package:tidyr':
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##     expand, pack, unpack

repo <- "https://raw.githubusercontent.com/langcog/experimentology/main"
sgf <- read_csv(file.path(repo, "data/tidyverse/stiller_scales_data.csv")) |>
  mutate(age_group = cut(age, 2:5, include.lowest = TRUE), 
         condition = condition |>
           fct_recode("Control" = "No Label", "Experimental" = "Label"))

## Rows: 588 Columns: 5
## ── Column specification ────────────────────────────────────────────────────────
## Delimiter: ","
## chr (3): subid, item, condition
## dbl (2): correct, age
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

sgf$age_centered <- scale(sgf$age, center = TRUE, scale = FALSE)
sgf$condition <- fct_relevel(sgf$condition, "Control")

mod <- glmer(correct ~ age_centered * condition + (1|subid) + (1|item), 
             family = "binomial", data = sgf)

summary(mod)

## Generalized linear mixed model fit by maximum likelihood (Laplace
##   Approximation) [glmerMod]
##  Family: binomial  ( logit )
## Formula: correct ~ age_centered * condition + (1 | subid) + (1 | item)
##    Data: sgf
## 
##      AIC      BIC   logLik deviance df.resid 
##    657.3    683.6   -322.7    645.3      582 
## 
## Scaled residuals: 
##     Min      1Q  Median      3Q     Max 
## -2.4195 -0.5688 -0.3756  0.6515  2.5418 
## 
## Random effects:
##  Groups Name        Variance Std.Dev.
##  subid  (Intercept) 0.05200  0.2280  
##  item   (Intercept) 0.07483  0.2735  
## Number of obs: 588, groups:  subid, 147; item, 4
## 
## Fixed effects:
##                                    Estimate Std. Error z value Pr(>|z|)    
## (Intercept)                         -1.4582     0.2156  -6.762 1.36e-11 ***
## age_centered                        -0.3767     0.1891  -1.992 0.046417 *  
## conditionExperimental                2.2613     0.2246  10.069  < 2e-16 ***
## age_centered:conditionExperimental   0.9237     0.2566   3.600 0.000318 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Correlation of Fixed Effects:
##             (Intr) ag_cnt cndtnE
## age_centerd  0.180              
## cndtnExprmn -0.617 -0.185       
## ag_cntrd:cE -0.155 -0.743  0.208