Consider the following information computed for differences between 25 pairs of scores: M = 5, s = 12. Based on this information, what is Cohen's d for the corresponding paired-samples t test, when rounded to two decimal places? When answering this question, please use a typical null hypothesis indicating no differences between the populations.单项选择题
A
d = 1.44
B
d = 0.50
C
d = 0.42
D
d = 0.86

Question

Consider the following information computed for differences between 25 pairs of scores: M = 5, s = 12. Based on this information, what is Cohen's d for the corresponding paired-samples t test, when rounded to two decimal places? When answering this question, please use a typical null hypothesis indicating no differences between the populations.单项选择题

A

d = 1.44

B

d = 0.50

C

d = 0.42

D

d = 0.86

BlackTom AI · Accepted Answer

We start by identifying the formula for Cohen's d in a paired-samples design. In this case, d = mean difference / standard deviation of differences.

Option A: d = 1.44
This would require a ratio around 1.44, which would imply a much larger mean difference relative to the standard deviation of differences than what we have. Given M = 5 and s = 12, the calculation 5/12 yields a much smaller value, so 1.44 is not consistent with the data.

Option B: d = 0.50
This value is plausible as an approximate effect size, but it does not match the exact calculation from the provided numbers. The precise ratio 5/12 equals 0.4167, which rounds differently than 0.50 when rounded to two decimals.

Option C: d = 0.42
This option aligns with the computed ratio. Computing directly: d = M / s = 5 / 12 = 0.416666..., which rounds to 0.42 when rounded to two decimal places. This is the value derived from the given information.

Option D: d = 0.86
This would require a substantially larger mean difference relative to the standard deviation, or a much smaller s, than what is provided. With M = 5 and s = 12, the resulting ratio is far from 0.86, making this option inconsistent with the data.

In summary, the only option that matches the direct computation from the given M and s is the one that equals approximately 0.4167, i.e., 0.42 when rounded to two decimals, while the others do not correspond to 5/12 and are thus incorrect.

类似问题

A sample is selected from a population with μ = 46, and a treatment is administered to the sample. After treatment, the sample mean is M = 48 with a sample variance of s2 = 16. Based on this information, what is the value of Cohen’s d?

Two samples from the same population both have M = 84 and s2 = 20, but one sample has n = 10 and the other has n = 20 scores. Both samples are used to evaluate a hypothesis stating that μ = 80 and to compute Cohen’s d. How will the outcomes for the two samples compare?

Calculate Cohen's D: Sample Size Group 1 = 19 Sample Size Group 2 = 16 Standard Deviation Group 1 = 4.2 Standard Deviation Group 2 = 5.5 Sample Mean Group 1 = 41.9 Sample Mean Group 2 = 43.5

Calculate Cohen's D: Sample Mean Difference Score (time 1 - time 2) = 1.7 Standard Deviation Difference Scores = 3.2 Sample Size = 39

Please consider the following information: Sample mean (M) = 50 Population mean (µ) = µM = 47 Sample standard deviation (s) = 4 Sample size (N) = 25 Based on this information, compute the effect size measure, Cohen's d. Please include at least two decimal places when reporting your answer.

According to Cohen's guidelines for the effect size measure d, which of the following would be an example of a medium effect size?

Consider the following information used for a one-sample t test: N = 100, µ = 30, s = 20, and M = 33. Based on this information, what is the measure of effect size, Cohen's d, rounded to two decimal places?

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