Introductory Research Methods: Pearson Correlation and T-Tests (VOCABULARY FLASHCARDS)

Vocabulary flashcards covering homoscedasticity, independence, Pearson correlation, and t-tests from the lecture notes.

Homoscedasticity

Homogeneity of variance across the data; a common assumption for parametric models; tested with Levene’s test; p<.05 suggests unequal variances; if violated, use alternatives like Welch’s t-test.

Homoscedastic

Describes data with equal variances across the range of values in the relationship.

Heteroscedastic

Describes data where variances differ across the range of values in the relationship.

Levene’s test

A test for homogeneity of variance; uses an F statistic; p<.05 indicates violation of equal variances.

Welch’s t-test

A t-test variant used when variances are unequal; does not assume equal variances.

Independence

Observations are independent (unrelated; not affecting each other); an assumption for parametric tests; checked by logic, not by a formal test.

Paired t-test (dependent samples)

Two related samples (same participants) analyzed as a paired comparison.

Independent t-test (between-subjects)

Two groups from different participants compared.

Pearson correlation (r)

Measures linear association between two variables; requires linearity, normality, homoscedasticity, independence; at least one variable is continuous; r ranges from -1 to 1.

Linear relationship

A straight-line relationship between two variables; required to interpret Pearson correlation.

Scatterplot

Graph plotting two variables to visually assess linearity before running a correlation.

r = 0

Indicates no linear relationship between the two variables.

r = 1

Indicates a perfect positive linear relationship.

r = -1

Indicates a perfect negative linear relationship.

Cohen’s d

A measure of effect size for t-tests that expresses the magnitude of group differences.

Degrees of freedom (df)

A value used in test statistics (e.g., t(df), r(df)) reflecting sample size and model structure.

p-value

Probability of observing data as extreme as the sample under the null hypothesis; commonly p<.05 indicates statistical significance.

t-test

Statistical test to compare two means; assumes normality, independence, and homoscedasticity; DV is continuous; IV is dichotomous; can be paired or independent.

DV continuous

Dependent variable that is measured on a continuous scale.

IV dichotomous

Independent variable that has two categories (groups or time points).