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.
What is the difference between correlational and experimental designs?
Experimental designs use random assignment, correlational designs do not.
What is quasi-experimental design?
A design with naturally occurring groups, lacking random assignment.
What is the Stroop test used for?
To measure cognitive interference by comparing reaction times.
What is the DV in the Stroop test?
Reaction times.
What is the IV in the Stroop test?
Congruency of the colour and word (congruent vs. incongruent).
What does a significant t-test indicate?
There is a statistically significant difference between the groups.
What does it mean if p > .05 in a t-test?
The difference between the groups is not statistically significant.
What is a randomised control trial (RCT)?
An experimental design where participants are randomly assigned to groups.
What is the benefit of random assignment?
It reduces bias and balances participant characteristics across groups.
Why is sample size important in a t-test?
Larger samples increase the power to detect significant effects.
What is statistical power?
The likelihood of detecting a true effect.
What is homoscedasticity?
Another term for homogeneity of variance.
What is heteroscedasticity?
When group variances are not equal.
What does a t-test compare?
The difference between group means relative to the variance.
Why should you report effect sizes along with p-values?
To indicate the practical significance of the results.
