Text: Almost everyone in GAO probably has worked on a case study at one time or another yet may be unfamiliar with what is meant, methodologically, by a case study.
Entailment: A case study is a common work task performed by employees at the GAO, however, many staff may be unfamiliar with what research scientists mean by a case study.
Contradiction: Staff working in the GAO will almost never perform a case study during employment.