In an earlier post, I mentioned I would be describing the ABC approach to inventory management in more detail. ABC is used in retail, and can be applied in healthcare, for example when trying to manage surgical inventory with reduced effort.
The critical path approach to project scheduling was developed at Dupont and Rand in the late 1950s. It involves defining project activities and their relative dependencies, and ascertaining what the sequence of critical tasks of longest duration is, and hence what the overall project timeline is which cannot be shortened — given that by definition there is no slack on the critical path. Note that there can be several near-critical paths.