AP Psychology Unit 2

Hindsight Bias

Thinking you “knew it all along” after learning the outcome.

Critical Thinking

Careful thinking that questions assumptions and looks for evidence

Theory 

A big idea that explains something and makes predictions.

Hypothesis 

A testable prediction based on a theory.

Operational Definition

A clear way of defining a variable so it can be measured.

Replication 

Repeating a study to see if the results hold true.

Case Study 

A deep study of one person or a small group.

Naturalistic Observation 

Watching and recording behavior in its natural setting.

Sampling Bias 

When the sample doesn’t fairly represent the whole group.

Population 

The entire group you want to study.

Random Sample 

Choosing participants by chance so everyone has an equal shot.

Correlation 

A relationship between two things (but not always cause).

Correlation Coefficient 

A number (from –1 to +1) measuring strength.

Scatterplot 

A graph of dots showing how two things relate.

Illusory Correlation 

Believing two things are related when they’re not.

Experimental Group 

The group that gets the treatment.

Control Group 

The group that does not get the treatment (comparison group).

Random Assignment 

Putting participants into groups by chance.

Double-Blind Procedure 

Neither participants nor researchers know who got the treatment.

Placebo Effect 

When people believe a fake treatment works.

Independent Variable 

The factor you change (the cause).

Confounding Variable 

A hidden factor that could mess up results.

Dependent Variable 

The outcome you measure (the effect).

Validity 

Does the test or experiment measure what it’s supposed to?

Descriptive Statistics 

Numbers that summarize data (like averages).

Histogram 

A bar graph showing frequency.

Mode 

The most common score.

Mean 

The average score.

Median 

The middle score.

Skewed Distribution 

When scores are lopsided (not balanced).

Range 

The gap between the highest and lowest scores.

Standard Deviation 

How spread out the scores are from the average.

Normal Curve 

A bell-shaped curve (most scores near the average).

Inferential Statistics 

Numbers that let you guess if results apply to a bigger group.

Statistical Significance 

When results are unlikely due to randomness.

Culture 

Shared ideas, values, and traditions of a group

Informed Consent 

Participants are told enough to decide if they want to join.

Debriefing 

Explaining the study afterward, including its purpose and any deception.