Week 6 - Comparing Groups (Continuous Variables)

What is a t-test used for?

Comparing the means between two groups.

When is a paired t-test used?

When data comes from the same group of individuals measured at different times.

List non-parametric equivalents to t-tests.

Mann-Whitney U test and Wilcoxon Signed-Rank test.

Define the Mann-Whitney U test.

A non-parametric test for comparing differences between two independent groups.

Define the Wilcoxon Signed-Rank test.

A non-parametric test for comparing differences between two related groups.

What is an independent samples t-test?

A test comparing the means of two independent groups.

What is the null hypothesis for an independent samples t-test?

The means of the two groups are equal.

What is the alternative hypothesis for an independent samples t-test?

The means of the two groups are not equal.

What assumptions must be met for a t-test?

Normality, independence, and homogeneity of variances.

What is homogeneity of variances?

The assumption that the variances in different groups are equal.

What is the Levene's test?

A test for assessing the equality of variances between groups.

What is the purpose of using graphs in data analysis?

To visually explore and summarize data before conducting statistical tests.

Define outliers.

Data points that are significantly different from other observations.

Why is it important to check for outliers?

Outliers can distort statistical analyses and affect results.

What is a hypothesis test?

A method for testing a claim about a population parameter.

What is the purpose of using a p-value in hypothesis testing?

To determine the significance of the results.

Explain the concept of statistical significance.

The likelihood that the observed effect is not due to chance.

What is a confidence interval in the context of hypothesis testing?

A range of values that is likely to contain the true population parameter.

What does it mean if a confidence interval does not include zero?

The effect is likely to be statistically significant.

Define effect size in the context of t-tests.

The magnitude of the difference between groups.