Quick comparison R2-CCC

comparison-r2-ccc.R

library(ggplot2)
library(dplyr)

# Creating dummy data
d <- data.frame(
    x = rnorm(100,10,3)
  ) %>% 
  mutate(
    y = jitter(x, factor = 800) - 5 * cos(x/10) 
  )

# You can see a good fit btw preds and obs, but not with the 1:1 line
d %>% 
  ggplot(aes(x = x, y = y)) + 
  geom_abline(slope = 1, intercept = 0, lty = 2, colour = "red") + 
  geom_smooth(method = "lm", colour = "royalblue") +
  geom_point() + 
  coord_equal()

# This problem in the predictions is overlooked by R-squared, 
# but taken into account by the CCC 
caret::R2(d$x, d$y)
epiR::epi.ccc(d$x, d$y)$rho.c