Can equating data be too old?

Asked by: Pearson / Evaluation Systems, in Session 4 — Michigan Test for Teacher Certification.

Answer given: “Yes, but it is dependent upon so many variables. Need to define the total time of reaching testing counts vs. rate of testing in next contract.”

Why it is still open. The answer names the trade without resolving it, and explicitly defers it to the next contract. It is the other half of How long does it take to accumulate enough examinees to equate?: accumulating 100 examinees slowly enough that the earliest of them no longer represent the current candidate population defeats the purpose of waiting for them.

For low-incidence fields this may mean there is no volume at which equating is both feasible and valid — which would strengthen the case for Escalate a field to the next group after two years below 100 and the standard-setting route.