ICC_intra

library("irr")
library("icc")
library("tidyverse")

df <- read_csv("ICC_intra.csv")

long_df1 <- df %>%
  select(`1`:`12`) %>% 
  gather("Grupo_antes", "Valor_antes")

Error in UseMethod("select_") : 
  no applicable method for 'select_' applied to an object of class "function"

long_df2 <- df %>%
  select(`a`:`l`) %>% 
  gather("Grupo_despues", "Valor_despues")

long_df <- bind_cols(long_df1, long_df2)

rm(df, long_df1, long_df2)
glimpse(long_df)

Observations: 96
Variables: 4
$ Grupo_antes   <chr> "1", "1", "1", "1", "1", "1", "1", "1", "2", "2", "2", "2", "2", "2", "2", ...
$ Valor_antes   <dbl> 187.045, 163.712, 145.996, 178.202, 168.263, 160.299, 193.085, 179.567, 20....
$ Grupo_despues <chr> "a", "a", "a", "a", "a", "a", "a", "a", "b", "b", "b", "b", "b", "b", "b", ...
$ Valor_despues <dbl> 190.024, 168.532, 144.930, 188.131, 168.160, 156.597, 200.128, 167.787, 18....

long_df <- long_df %>% 
  select(Valor_antes, Valor_despues)

icc(long_df, model = "twoway", type = "agreement")

 Single Score Intraclass Correlation

   Model: twoway 
   Type : agreement 

   Subjects = 96 
     Raters = 2 
   ICC(A,1) = 0.996

 F-Test, H0: r0 = 0 ; H1: r0 > 0 
 F(95,93.9) = 554 , p = 8.93e-103 

 95%-Confidence Interval for ICC Population Values:
  0.995 < ICC < 0.998