“…In addition, they outlined in much greater detail than previous classroom research the reliabilities of their extensive test measures, and they were the first explicitly to employ analysis of covariance to adjust for initial differences-although researchers from the beginning of the Journal's publication had shown concern and attempts to adjust for lack of equivalence between treatment groups. Also to the credit of Clark and Clark and of Blickenstaff and Woerdehoff, they sampled student attitudes toward the instructional variables, a practice that up to that time had been neglected in classroom studies (sam-pling of student attitudes toward instruction was undertaken more extensively in the 1970s and afterwards, as in Moody, 1976, a correlational study only; Benmaman, Moore, Morgan, & Rowe, 1982;Joiner, 1977;Nieman & Smith, 1978;Schulz, 1977;and Swaffar & Woodruff's 1978 review of several correlational studies at the University of Texas).…”