Question 1

Which statistical test would be most appropriate to compare the mean scores of two independent groups when the data are normally distributed and variances are equal?

Accepted Answer

Independent samples t-test

Question 2

A researcher wants to determine if a new medication improves walking ability in patients with multiple sclerosis compared to a placebo. Which is the null hypothesis for this study?

Accepted Answer

There is no difference in walking ability between the medication and placebo groups.

Question 3

Which of the following is a key assumption for parametric tests such as the independent samples t-test?

Accepted Answer

The data are normally distributed.

Question 4

A researcher uses a paired t-test to compare pre- and post-treatment scores in the same group of patients. What is the main reason for choosing a paired t-test?

Accepted Answer

The measurements are repeated on the same subjects.

Question 5

If the p-value from a t-test is less than 0.05, what is the most appropriate conclusion?

Accepted Answer

The null hypothesis is rejected.

Question 6

Which formula is used to calculate the t-statistic for independent samples with equal variances?

Accepted Answer

$$ t = \frac{\bar{X}_1 - \bar{X}_2}{s_p \sqrt{\frac{1}{n_1$} + \frac{1}{n_2$}}} $$

Question 7

A study finds a statistically significant difference in mean blood pressure between two groups. What additional step should be taken to interpret the practical significance of this result?

Accepted Answer

Calculate the effect size.

Question 8

Which of the following best describes a non-parametric test?

Accepted Answer

It is used when data do not meet parametric assumptions.

Question 9

In SPSS, what is the first step to verify the results of a t-test for independent groups?

Accepted Answer

Verify the result of the Levene’s test for equality of variances.

Question 10

A researcher is interested in whether patients with COPD walk slower on a 6-minute walk test than healthy controls. Which statistical test should be used?

Accepted Answer

Independent samples t-test

Question 11

Which of the following is NOT a step in interpreting the results of a t-test for independent groups?

Accepted Answer

Ignore the difference in variances.

Question 12

What is the main difference between a paired t-test and an independent samples t-test?

Accepted Answer

Paired t-test is used when the same subjects are measured twice.

Question 13

Which effect size measure is commonly used to interpret the magnitude of difference between two means?

Accepted Answer

Cohen’s d

Question 14

A researcher finds that the difference in means between two groups is statistically significant but the effect size is small. What does this imply?

Accepted Answer

The difference is statistically significant but may not be meaningful in practice.

Question 15

Which of the following is the correct formula for Cohen’s d?

Accepted Answer

$$ d = \frac{\bar{X}_1 - \bar{X}_2}{s_p} $$

Question 16

When should a researcher use a non-parametric test instead of a parametric test?

Accepted Answer

When the data do not meet the assumptions of parametric tests.

Question 17

A researcher wants to test whether a training program improves performance by comparing scores before and after the program in the same group. Which test should be used?

Accepted Answer

Paired t-test

Question 18

Which of the following is a real-world example of using a paired t-test?

Accepted Answer

Measuring blood pressure before and after medication in the same patients.

Question 19

What is the alternative hypothesis in a t-test for independent groups?

Accepted Answer

The means of the two groups are not equal.

Question 20

Which step is necessary before interpreting the results of a t-test in SPSS?

Accepted Answer

Verify the result of the Levene’s test for equality of variances.

Statistical Methods for Mean Differences in Health Sciences

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