A study will investigate the effectiveness of a new textbook. The samples (n = 30 and n= 35) included in the study are taught by two professors. Which
of the following are possible limitations of the study? Select all that apply.
A. The number of samples is too small.
B. The professors may differ in number of years teaching and overall
experience.
C. The sample size is too small.
D. The professors may have different teaching techniques, which
contribute to the overall effectiveness of the textbook.