Research Methods in Psychology: Case Studies and Correlational Studies

Case Studies:

• In-depth study of one individual, often for rare or unique cases (e.g., traumatic brain injury like Phineas Gage).

• Provides useful data for generating hypotheses and 'existence proofs' (showing something can happen).

• Weakness: Results cannot be generalized to the broader population.

Correlational Studies:

• Examine the relationship between two variables; allow for prediction.

• Positive Correlation: As one variable increases, the other also increases (e.g., height and weight, r = +0.47); or as one decreases, the other decreases.

• Negative Correlation: As one variable increases, the other decreases (e.g., toothbrushing and tooth decay, r = -0.71).

• Strength of Correlation: Indicated by the absolute value of the correlation coefficient, r. The closer |r| is to 1, the stronger the relationship. r = 0 indicates no relationship.

• Direction: The positive or negative sign of r indicates the direction of the relationship, not its strength (e.g., -0.71 is a stronger correlation than +0.45).

• Crucial Principle: Correlation does not imply causation. A third variable often explains the relationship between two correlated variables (e.g., warm weather causes both increased ice cream sales and drownings).