For example, the following courses are proposed at the same department of the same university:

 - 12 credits (48+72 hours)
 - 9 credits (24+12 hours)
 - 9 credits (24+0 hours)
 - 6 credits (24+36 hours)

All of the courses I refer to are Master's level. "x+y" hours means x hours of lectures and y hours of practical sessions.

Intuitively, one would suppose that the number of credits should be somehow proportional to the number of hours.