Robb Carefully Designed a Study to Test a Method for Reducing

Multiple Choice

Robb carefully designed a study to test a method for reducing test anxiety among students.On the day he conducts his post-test,a broken water main nearby results in jack hammering and other construction sounds that are seem to be distracting research participants.Robb's ability to detect differences among his groups may have been compromised by ____.

A) low reliability of the measure
B) random heterogeneity of participants
C) poor reliability of treatment implementation
D) random irrelevancies in the setting