*Psychology Research Fundamentals

Correlation Types

• Positive Correlation: Both variables move in the same direction.

• Negative Correlation: Variables move in opposite directions.

Correlation Coefficient ($r$)

• A number between $-1.0$ and $+1.0$.

• Direction:

  • Positive (+$R): Variables move together.

  • Negative ($-$R): Variables move opposite.

• Strength:

  • Closer to $0$: Weak or no relationship.

  • Closer to $+1.0$ or $-1.0$: Strong relationship.

  • General guidelines: $.3$ for weak/moderate, $.51$ for moderate to strong, $.7+$ for strong.

Correlational Research Purpose

• Used to predict behavior or outcomes based on established patterns.

Logic of Experimentation

• Involves controlled manipulation of a variable to observe its outcome and infer causal relationships ($Controlled \rightarrow Manipulation \rightarrow Outcome \rightarrow Inference$).

Independent vs. Dependent Variables

• Independent Variable (IV): The factor manipulated by the researcher (the "cause").

• Dependent Variable (DV): The outcome measured, which changes in response to the IV (the "effect").

• The IV influences the DV.