Aresearcher designs an experiment by manipulating the following variables: method of presenting material (visual, auditory); difficulty level (easy, difficult); and amount of material (low, moderate, high). for a completely independent groups design with 10 participants per group, how many participants would the researcher need

the researcher would need 120 participants.

Explanation:

When dealing with many variables it's possible to find the maximum amount of combinations possible by multiplying the number of variables.

So, we have 2, visual and auditory, 2 levels of difficulty, the amount of material varying to low, moderate and high (3), and the numbers of  participants to each unique group is 10.

2·2·3·10 = 120

We can easily find the total amount of participants using this simples equation above.

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