Compute the effect size in a one-sample t-test with a sample size of n = 66 and a test statistic of t = 2.27. How is the effect size interpreted based on Cohen's guidelines?
A) 0.28, a small effect
B) 0.38, a medium effect
C) 0.03, a small effect
D) 0.63, a large effect

Question

Quizplus · Accepted Answer

The effect size (Cohen's d) in a one-sample t-test can be calculated as $d = \frac{t}{\sqrt{n}}$, where $t$ is the test statistic and $n$ is the sample size. Plugging in the given values, $d = \frac{2.27}{\sqrt{66}} \approx 0.28$. According to Cohen's guidelines, an effect size of 0.2 is considered small, 0.5 medium, and 0.8 large, making 0.28 a small effect.

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