I'm trying to use IRT to select the best items for a one-factor scale that has 20 items. I was wondering what I need to be looking at if I wanted to select 5 or so items from these items (for a short version of the scale). I would really appreciate any suggestions/references!
Higher slope values are better - this are discrimination parameters, the higher the slope, the greater the ability of the item to distinguish ability.
A range of difficulty parameters - or difficulty parameters in the area where you want the measure to have the most precision.