This question is about cost drivers, and chosing appropriate cost drivers for purposes or cost estimation and cost management.

A research institute is developing new drugs. The research department sends out blood samples for examination to an external pathology lab. What is the cost driver of this activity?

So I have answer:

For cost estimation purposes: Number of blood samples sent

For cost management purposes: Skill level of staff

Where is the difference between cost estimation and cost management. And why the cost driver in cost management purpose is Skill level of staff?