If the same observers rate students' on-task behavior before and after an experimental intervention, their ratings are susceptible to an internal-validity threat known as:
A) statistical regression.
B) experimental treatment interaction.
C) an instrumentation effect.
D) a testing effect.

Question

Quizplus · Accepted Answer

An instrumentation effect occurs when there are changes in the measurement instrument (in this case, the observers' criteria or method of rating) over time, which can affect the consistency and validity of the measurements before and after an intervention.

If the Same Observers Rate Students' On-Task Behavior Before and After