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A sample of passengers flying on small planes gave a mean total weight (passenger weight including shoes, clothes, and carry-on) of 200 pounds and a standard deviation of 60 pounds.
-Based on Cohen's interpretation, this effect is
A) a small effect, not obvious without statistics.
B) a medium effect, obvious to careful observers.
C) a large effect, obvious to most observers.

Question

Use the following information for questions:
 A sample of passengers flying on small planes gave a mean total weight (passenger weight including shoes, clothes, and carry-on) of 200 pounds and a standard deviation of 60 pounds.
-Based on Cohen's interpretation, this effect is
A) a small effect, not obvious without statistics.
B) a medium effect, obvious to careful observers.
C) a large effect, obvious to most observers.

Quizplus · Accepted Answer

The effect size is calculated as the mean difference divided by the standard deviation. In this case, the effect size is 200/60 = 3.33. According to Cohen's interpretation, an effect size of 0.2 is considered small, an effect size of 0.5 is considered medium, and an effect size of 0.8 is considered large. Therefore, the effect size of 3.33 is considered large, which means that the effect is obvious to most observers.

Use the Following Information for Questions