Use the guidelines to evaluate the study. Discuss flaws that you see in the study. An educational researcher wishes to compare the effectiveness of two different math textbooks. She has the tenth graders at one school use the first book for one year and the tenth graders at another school use the second textbook for one year. At the end of the year, she gives the same math test to both classes and compares the results.

Question

What will be an ideal response?

Answer 1

There are confounding variables. In order to evaluate which of the two books is better it is important that the two groups be alike, in every respect other than the textbook used. In this case there are other differences between the two groups - they have different teachers, also one school may have students who work harder or have a greater aptitude for math. One of the classes may already have a higher level of math at the beginning of the study. If there is a large difference between the test scores for the two classes it will be impossible to know whether this is because of the textbook or because of the other confounding variables.