R/ICC2.CI.R

In psychometric: Applied Psychometric Theory

"ICC2.CI" <-
function (dv, iv, data, level=.95)
 {

  dv <- data %>% dplyr::select({{dv}}) %>% purrr::reduce(c)
  iv <- data %>% dplyr::select({{iv}}) %>% purrr::reduce(c) %>% factor()
  
  mod <- aov(dv ~ as.factor(iv), na.action=na.omit)
  icc <- ICC2(mod)
  tmod <- summary(mod)
  df1 <- tmod[[1]][1,1]
  df2 <- tmod[[1]][2,1]
  Fobs <- tmod[[1]][1,4]
  n <- df2/(df1+1) # k-1
  noma <- 1- level
  Ftabl <- qf(noma/2, df1, df2, lower.tail=F)
  Ftabu <- qf(noma/2, df2, df1, lower.tail=F)
  Fl <- Fobs/Ftabl
  Fu <- Fobs*Ftabu
  lcl <- 1-1/Fl
  ucl <- 1-1/Fu
  mat <- data.frame(LCL=lcl, ICC2=icc, UCL=ucl)
 return(mat)
 }