RESEARCH · METHODS · EVIDENCE
Describe an association
Browse statistics lessons
- Statistics for research
- Center and spread
- Distributions and standard errors
- Statistical inference
- P-values and interpretation
- Critical values and test direction
- Compare means with t-tests
- Read t-test output
- Compare several means with ANOVA
- Read an ANOVA table
- Analyze categorical counts
- Read chi-square output
- Describe an association
- Read correlation results
- Interpret a regression model
- Choose a statistical method
- Statistics resources
Pearson’s r describes the direction and strength of a linear relationship between two numeric variables. Inspect a scatterplot for nonlinearity, outliers, and subgroup patterns before relying on r.
Spearman’s rank correlation addresses a monotonic rank relationship and answers a different question. A correlation near zero does not rule out a nonlinear pattern, and correlation alone does not establish causation.
References: NIST statistical handbook