IPEDS data on “Instruction” includes departmental research (which of course isn’t instruction), but that is how a federal OMB circular allows it to be accounted. So someone can be taking a semester off to publish something or submit a research proposal and it is accounted for as “Instruction”, which is used in these rankings. It also tends to be significantly higher for universities that have medical school (look at UCLA vs. Berkeley), but of course none of that is really relevant to undergraduate instruction.