1. Longitudinal design:

A method following the same group of participants over an extended period to observe changes across time.

2. Dependent variable:

The outcome factor that is measured; it changes in response to manipulations of the independent variable.

3. Descriptive statistics:

Numerical data used to summarize, organize, and describe the basic characteristics of a specific sample dataset.

4. Inferential statistics:

Numerical methods that allow researchers to generalize findings from a sample to make broader claims about a population.

5. Experimental group:

The group of participants in an experiment who receive the active treatment or condition being tested.

6. External validity:

The extent to which the findings of a study can be generalized to other people, settings, and times.

7. Longitudinal research:

Same as longitudinal design) A study that tracks the same individuals repeatedly over an extended timeline.

8. Hypothesis:

A specific, testable prediction derived logically from a theory about what will happen under particular conditions.

9. Theory:

A broad, systematic set of ideas that integrates and explains observed phenomena while predicting future behaviors.

10. Surveys:

A data-collection tool utilizing questionnaires or interviews to gather self-reported attitudes, beliefs, or behaviors from a group.

11. Case studies:

An in-depth, detailed examination of a single individual or a very small group to uncover universal principles.

12. Correlational research:

A non-experimental approach that measures the statistical relationship between two or more naturally occurring variables.

13. Extraneous variable:

: Any variable other than the independent variable that could potentially influence the outcome of a study.

14. Experimental bias:

The unintentional tendency of researchers to influence study outcomes to match their expectations or hypotheses.

15. Control group:

The baseline group of participants who do not receive the active treatment, serving as a comparison standard.

16. Median:

The middle score in a distribution; half the scores are above it and half are below it.

17. Mode:

The most frequently occurring score or value in a given distribution of data.

18. Mean:

The arithmetic average of a distribution, calculated by adding the scores and dividing by the total number of scores.

19. Naturalistic observation:

Observing and recording behavior in its natural environment without trying to manipulate or control the situation.

20. Hindsight bias:

The psychological tendency to believe, after learning an outcome, that you could have successfully predicted it ("I knew it all along").

21. False consensus effect:

The cognitive bias where an individual overestimates the degree to which others share their opinions and behaviors.

22. Confirmation bias:

The tendency to search for, interpret, and recall information in a way that confirms pre-existing beliefs.

23. Placebo effect:

Experimental results caused by expectations alone; behavior changes when a participant falsely believes they received a treatment.

24. Random assignment:

Sorting participants into groups by chance, ensuring every person has an equal probability of placement to minimize baseline differences.

25. Operational definition:

A precise, objective statement defining exactly how a variable will be manipulated or measured in a specific study.

26. Judgmental overconfidence:

The tendency to be more confident in the accuracy of our judgments and beliefs than we actually are objective.

27. Representative sample:

A sample that accurately mirrors the characteristics, demographics, and diversity of the target population.

28. Statistics:

The branch of mathematics focused on collecting, organizing, analyzing, interpreting, and presenting numerical data.

29. Confounding:

A situation where an extraneous variable correlates with the independent variable, confusing the results and threatening internal validity.

30. Positive correlation

: A relationship where two variables move in the same direction; as one increases, the other increases.

31. Introspection:

An early psychological technique where individuals look inward to examine and report their own conscious thoughts and feelings.

32. External validity:

(Repeated term) The degree to which study results can hold true outside the specific lab setting for other populations.

33. Internal validity:

The degree to which an experiment can confidently establish a cause-and-effect relationship without alternative explanations.

34. Population:

The entire group of individuals about whom a researcher wants to draw conclusions.

35. Sample:

A smaller subset of individuals selected from the larger population to actually take part in the research study.