Question: Correlation Versus Causation

If correlation does not imply causation, what does it imply? Are there ever any circumstances when a correlation can be interpreted as evidence for a causal connection between two variables? If yes, what circumstances?

Required Readings: Use your Warner text, Applied Statistics: From Bivariate Through Multivariate Techniques, to complete the following:

1. Read Chapter 7, "Bivariate Pearson Correlation," pages 261-314. This chapter addresses the following topics:

• Assumptions of Pearson's r.

• Preliminary data screening for Pearson's r.

• Statistical significance tests for Pearson's r.

• Factors influencing the magnitude and sign of Pearson's r.

• Effect-size indexes.

• Interpretation of Pearson's r values.

2. Read Chapter 8, "Alternative Correlation Coefficients," pages 315-343. This chapter addresses the following topics:

• Correlations for rank or ordinal scores.

• Correlations for true dichotomies.

• Correlations for artificial dichotomies.

• Chi-square test of association.

Jia, Y., Konold, T. R., & Cornell, D. (2015). Authoritative school climate and high school dropout rates. School Psychology Quarterly. doi:10.1037/spq0000139

Anderson, C. A., & Bushman, B. J. (2001). Effects of violent video games on aggressive behavior, aggressive cognition, aggressive affect, physiological arousal, and prosocial behavior: A meta-analytic review of the scientific literature. Psychological Science, 12(5), 353-359.

Discussion: Interpreting Correlations

A meta-analysis (Anderson & Bushman, 2001) reported that the average correlation between time spent playing video games ( X) and engaging in aggressive behavior ( Y) in a set of 21 well-controlled experimental studies was .19. This correlation was judged to be statistically significant. In your own words, what can you say about the nature of the relationship?