Experiments vs. Correlational Research

Need a strong understanding of experiments and correlational research for AP Psychology.
Distinguish between the two, as not all research is an experiment.
Use "research" or "study" as generic terms instead of overusing "experiment."
Focus on discerning between experiment and correlational research when analyzing studies.

The scientific method is used in psychology to evaluate ideas through observation and analysis.
Psychologists critically think, observe behaviors, test variables, and draw conclusions.

A theory is an explanation using integrated principles to organize observations and predict behaviors or events.
Theories summarize observations and inspire further research.
Example: Theory that sleep affects memory.
Better sleep correlates with increased answering questions in class and improved test scores.
Theories need to produce testable hypotheses to prove accuracy.

A hypothesis is a testable prediction implied by a theory.
It should be falsifiable, meaning it can be disproven by observation or experiment.
Example hypothesis: "If people are sleep deprived, then they will remember less or score lower on a test than those who got better sleep."

A carefully worded statement of exact procedures used in a research study.
Important in psychology because complex concepts (e.g., personality) can be measured in various ways.
If measuring personality, clearly define the measurement method.

Repeating the essence of a research study to see if the initial findings can be reproduced.
Affirms or challenges theories.
Operational definitions allow replication by clearly articulating the procedures of the original study.
AP level emphasizes that operational definitions need to be measurable and quantifiable.
Specific procedures for research allow for replication and reduce bias.
Example: Sleep deprivation defined as two hours less than a person’s natural sleep requirement.
Human intelligence measured with scores on an intelligence test (numerical value).
Operationalizing a study helps others replicate and produce comparable results.
Replication is confirmation.

A descriptive technique in which one individual or group is studied in-depth to reveal universal principles.
Unique individuals or groups are examined closely.
Helpful but potentially not generalizable to a larger population.

Observing and recording behavior in naturally occurring situations without manipulation or control.
Animal studies in the wild involve naturalistic observation.
Descriptive and informative but doesn't explain why the behavior occurs.
Often a starting point for further research.

A tool for obtaining self-reported attitudes or behaviors of a group.
Requires a representative random sample of the population.
Sample needs to mirror the larger population.
Results from a representative sample can be generalized to the larger population.
Survey writers must be wary of wording bias and sampling errors.

A flawed sampling process that produces an unrepresentative sample.
Convenience sampling: Sampling people who are easily accessible.
Random sampling/selection: Each member of the population has an equal chance of being included.
Population: The entire group being studied.
Sample: The people actually studied.

Correlation measures the extent to which two factors vary together and how well one predicts the other.
Variables are factors that can vary and are feasible and ethical to measure.
Correlational research examines the relationship between two variables.
Descriptive measures can show how variables coincide.
Knowing how closely variables are correlated can help make predictions.
Correlations do not show cause-and-effect relationships; correlation is not causation.

A statistical index of the relationship between two variables.
Ranges from -1 to +1.
Values above 1 or below -1 are not possible.
+1 or -1 signifies a perfect correlation (rare).
Values are typically between 0 and 1 (positive or negative decimals).
Coefficients can be positive or negative, describing the direction of the relationship.