1 Data

pacman::p_load(mlmRev, tidyverse, lme4, nlme)

dta_1 <- read.table("C:/Users/ASUS/Desktop/data/demo1.txt", header = T)
dta_2 <- read.table("C:/Users/ASUS/Desktop/data/demo2.txt", header = T)

1.1 Grand Means of score for dat_1 &_2

summary(dta_1$Score)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   11.00   51.00   55.00   62.11   93.00   97.00
summary(dta_2$Score)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   11.00   51.00   53.00   57.44   91.00   97.00

2 Null Model

2.1 M1(dta_1)

summary(m1 <- lmer(Score ~ (1|School), data = dta_1))
## Linear mixed model fit by REML ['lmerMod']
## Formula: Score ~ (1 | School)
##    Data: dta_1
## 
## REML criterion at convergence: 51.5
## 
## Scaled residuals: 
##     Min      1Q  Median      3Q     Max 
## -1.3280 -0.4745  0.0000  0.4608  1.3553 
## 
## Random effects:
##  Groups   Name        Variance Std.Dev.
##  School   (Intercept) 1679     40.976  
##  Residual                5      2.236  
## Number of obs: 9, groups:  School, 3
## 
## Fixed effects:
##             Estimate Std. Error t value
## (Intercept)    53.01      23.67    2.24

2.2 M2(dta_2)

summary(m2 <- lmer(Score ~ (1|School), data = dta_2))
## Linear mixed model fit by REML ['lmerMod']
## Formula: Score ~ (1 | School)
##    Data: dta_2
## 
## REML criterion at convergence: 80.4
## 
## Scaled residuals: 
##      Min       1Q   Median       3Q      Max 
## -1.36734 -0.34286 -0.02776  1.07153  1.13999 
## 
## Random effects:
##  Groups   Name        Variance Std.Dev.
##  School   (Intercept) 104.2    10.21   
##  Residual             967.8    31.11   
## Number of obs: 9, groups:  School, 3
## 
## Fixed effects:
##             Estimate Std. Error t value
## (Intercept)    56.36      12.01   4.692

3 ICC

3.0.1 dta_1

library(ICC)
ICCbare(School, Score, dta_1)
## Warning in ICCbare(School, Score, dta_1): 'x' has been coerced to a factor
## [1] 0.9969128

3.0.2 dta_2

ICCbare(School, Score, dta_2)
## Warning in ICCbare(School, Score, dta_2): 'x' has been coerced to a factor
## [1] 0.1008126