Research Methods AP psych

Case Study

A research method that involves an in-depth analysis of a person, group, or phenomenon.

Naturalistic observation

A research method where subjects are observed in their natural environment without manipulation.

Survey

A method of gathering information from individuals, often through questionnaires.

Wording Effect

Question phrasing changes results, e.g., 'Do you agree…' vs 'How do you feel about…'.

Random Sampling

Everyone has an equal chance to be picked, such as picking names randomly from a list.

Population

The whole group you want to study, e.g., all high school students.

Representative Sample

A small group that matches the population, e.g., students from all grades and groups.

Convenience Sample

An easy-to-reach group, such as only surveying your friends.

Correlation

A statistical measure that describes the extent to which two variables change together.

Positive Correlation

Two variables move up or down together.

Negative Correlation

Two variables move away from one another.

Experimental Group

The group exposed to treatment in an experiment.

Control Group

The group exposed to placebo/fake or less of treatment.

Independent Variable

What is being manipulated in an experiment.

Dependent Variable

What is being measured in an experiment.

Random Assignment

How you place participants into certain groups.

Double-Blind Study

Neither the participants nor the researchers know who is receiving the real treatment or the placebo.

Single-Blind Study

The participants do NOT know which group they're in (experimental or control), but the researchers do know.

Placebo Effect

When people's expectations influence how they feel or behave.

Institutional Review Board (IRB)

A group that reviews and approves all research involving humans to ensure it's ethical and safe.

Informed Consent

Participants must be told what the study involves and agree to take part voluntarily.

Confidentiality

Researchers must keep all participants' personal information private and secure.

Deception

Researchers mislead or withhold information about the true purpose of the study when necessary.

Debriefing

After the experiment ends, researchers explain the true purpose of the study and reveal any deception used.

Confederates

People who work with the researcher but * participants to influence or create certain situations.

P-value 0.05

The p-value tells you how likely it is that your experiment's results happened by chance, measuring statistical significance.

P-value

If p < 0.05, it means there's less than a 5% chance the results happened randomly.

Statistically significant

In psychology, this means the results are considered statistically significant.

Effect size

Effect size measures how strong or large the difference or relationship is — not just whether it's significant.

Histogram

A graph that shows the frequency (how often) certain values appear in a continuous dataset (like test scores or reaction times).

Bar Graph

A bar graph compares different categories or groups.

Scatterplot

Shows the relationship (correlation) between two variables.

Claim

Your main statement or position — the central idea you're arguing for.

Defensible

Claim or argument is one you can support with clear reasoning or evidence from psychology.

Hindsight bias

The tendency to believe, after learning an outcome, that one would have predicted it all along.

Random sample

A sample where every member of the population has an equal chance of being chosen.

Critical thinking

Thinking carefully and evaluating evidence before accepting conclusions.

Overconfidence

Being more confident in one's knowledge or predictions than is justified.

Theory

An explanation that organizes observations and predicts behaviors or events.

Correlation coefficient

A number (-1 to +1) that measures the strength and direction of a relationship between two variables.

Hypothesis

A testable prediction based on a theory.

Quantitative

Data measured in numbers or amounts.

Operational definition

A clear, precise way to define and measure a variable.

Illusory correlation

Believing there's a relationship between two things when none exists.

Qualitative

Data based on descriptions, observations, or opinions rather than numbers.

Replication

Repeating a study to see if the results are consistent.

Experiment

A method in which researchers manipulate one variable to observe its effect on another while controlling other factors.

Meta-analysis

Combining results from many studies to determine overall trends.

Double-blind procedure

Both participants and researchers don't know who receives the real treatment or placebo.

Null hypothesis

A statement that there is no effect or relationship between variables.