An educational researcher has designed two different methods for teaching a statistics course and would like to investigate which is more effective.He designs an experiment as follows.He will obtain a group of volunteer statistics students.Volunteers will be randomly assigned to one of two groups.Group 1 will be taught the statistics course by Anna Clark using method A and group 2 will be taught by Bob Beauman using method B.At the end of the semester,students will all take the same test.Then the scores for the two groups will be compared.The person grading the tests will be blinded to which group students were in.Identify the most serious flaw in this experiment.

A) There is a confounding variable - namely the teacher.
B) There is no blocking.
C) The person grading the tests may have been biased.
D) Since there is no random assignment,there could be lurking variables.
E) Volunteers should have been selected randomly.

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Zybrea Knight · Accepted Answer

Final Answer : A, Explanation :  The most serious flaw in this experiment is that there is a confounding variable - the teacher. The study is comparing two different teaching methods, but the effectiveness of the methods could be influenced by the skill or charisma of the teacher. To control for this, the experiment should use a crossover design where both teachers use both teaching methods with different groups of students. Alternatively, multiple teachers should be used for each method across both groups of students.

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