Item and Test Characteristic Curves for multiple groups

tidyverse
,
10

It looks like you can resuse the code from GGplot - Test Information Functions for multiple groups by creating the analogue of groups immediately after you first create the table l.format -- you can leave the call to factor() until later:

items <- 
l.format %>%
group_by(item) %>%
arrange(abs(P.1-0.5)) %>% 
slice(1) %>% 
ungroup() %>% 
arrange(Theta) %>% 
pull(item)

Then just replace group and groups by item and items in the ggplot() section of the code from GGplot - Test Information Functions for multiple groups. Does this work for you?