Suppose that a study compares the means of two groups. There are 40 males in Group 1 and 35 females in Group 2. The degrees of freedom for this study when using the t-test for the difference between means is:

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When comparing the means of two independent groups with a t-test, the common approach is to use the pooled-variance t-test which assumes equal variances; the degrees of freedom in that case are n1 + n2 − 2. Here, Group 1 has 40 individuals and Group 2 has 35 individuals, so the calculation is 40 + 35 − 2 = 73.

Option a. 73: This matches the standard formula for the simple two-sample t-test with equal variances and uses all observations from both groups minus 2 for the estimated means. It is therefore the correct df in this scenario.

Option b. 74: A tempting miscalculation could come from adding the group sizes and then subtracting 1, i.e., 40 + 35 − 1 = 74. However, that would correspond to degrees of freedom for estimating a single pooled mean, which is not the usual df formula for the two-sample t-test.

Option c. 75: This would result from subtracting 2 from a total of 77 observations, which would imply a total sample size of 77. But the actual total is 40 + 35 = 75 observations, so df cannot be 75 in this standard setup.

Option d. 72: This option reflects subtracting 3 from the total sample size 75, which does not align with the standard df calculation for a two-sample t-test with equal variances. It would suggest two fewer parameters estimated beyond the two group means, which is not the usual practice here.

In summary, the correct degrees of freedom for a two-group means comparison with n1 = 40 and n2 = 35 is 73, since you pool the two sample sizes and subtract 2 for the two estimated means.

MKF5912 - S1 2025 Week 10 - Quiz

Suppose that a study compares the means of two groups. There are 40 males in Group 1 and 35 females in Group 2. The degrees of freedom for this study when using the t-test for the difference between means is:

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MKF5912 - S1 2025 Week 10 - Quiz

Suppose that a study compares the means of two groups. There are 40 males in Group 1 and 35 females in Group 2. The degrees of freedom for this study when using the t-test for the difference between means is:

查看解析

登录即可查看完整答案

类似问题

The degrees of freedom of a 4 x 5 table is:

What happens as the df of a dataset is increased?

​A researcher reports df = 18 for a repeated-measures t statistic. This research study used a total of n = 19 participants.

A repeated-measures study using a sample of n = 20 participants would produce a t statistic with df = ____.​

If the population variance is unknown, then a degree of freedom is lost in the calculation of sample variance.

In a contingency table, what does the degrees of freedom indicate?

Based on the information in Question 1, what were the degrees of freedom (DF) for the interaction of color and style, C?

What concept do "degrees of freedom" represent in statistical analysis?

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考试浏览器助手

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论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

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学校历年真题

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智能匹配练习

希望你的学习变得更简单

A researcher reports df = 18 for a repeated-measures t statistic. This research study used a total of n = 19 participants.

A repeated-measures study using a sample of n = 20 participants would produce a t statistic with df = ____.