The sheepskin effect doesn't directly measure the effect of having a degree vs having exactly the same experience/education but no degree. This is because the

The sheepskin effect doesn't directly measure the effect of having a degree vs having exactly the same experience/education but no degree. This is because the person who gets the degree after 4 years might on average have worked a lot harder, and learned a lot more than the person who studies for 4 years but doesn't get the degree.