4. T TESTS Flashcards
What is a t-test used for?
To compare the means of two groups or conditions.
What is the independent variable (IV) in a t-test?
A categorical variable with two levels.
What is the dependent variable (DV) in a t-test?
A continuous variable (interval or ratio data).
What are the two main types of t-tests?
Independent t-test and paired-samples t-test.
What is an independent t-test?
A test comparing two different groups (between-subjects design).
What is a paired-samples t-test?
A test comparing two conditions within the same group (within-subjects design).
What is the homogeneity of variance assumption?
The assumption that the variances of the two groups are equal.
What test checks homogeneity of variance?
Levene’s test.
What does a significant Levene’s test indicate?
Variances are not equal, so you use Welch’s t-test.
What is Welch’s t-test?
A t-test used when homogeneity of variance is violated.
What is the null hypothesis in a t-test?
The means of the two groups are equal.
What is the alternative hypothesis in a t-test?
The means of the two groups are different.
What is a p-value?
The probability of observing the data if the null hypothesis is true.
What does p < .05 indicate?
The result is statistically significant.
What is a Type I error?
Rejecting a true null hypothesis (false positive).
What is a Type II error?
Failing to reject a false null hypothesis (false negative).
What is effect size?
A measure of the magnitude of the difference between groups.
What is Cohen’s d?
An effect size measure for t-tests.
What is a small effect size according to Cohen’s d?
d ≈ 0.2
What is a medium effect size according to Cohen’s d?
d ≈ 0.5
What is a large effect size according to Cohen’s d?
d ≈ 0.8
What does a confidence interval (CI) represent?
The range within which the true effect size is likely to fall.
What is a narrow confidence interval?
A precise estimate of the effect size.
What is a wide confidence interval?
An imprecise estimate of the effect size.
