Psychology Research Methods and Data Analysis Key Concepts

AP Psych - Unit 0

Cultural norms

Shared rules/expectations in a society about what behaviors are normal or acceptable.

Confirmation bias

The tendency to search for or interpret information in a way that supports what you already believe.

Hindsight bias

The "I knew it all along" effect; believing after something happens that you could have predicted it.

Overconfidence

The tendency to be more confident than correct about your judgments or abilities.

Independent variables (IV)

The variable the researcher changes/manipulates in an experiment.

Confounding variables

Uncontrolled variables that could affect the results and make it unclear what caused the outcome.

Dependent variables (DV)

The variable being measured; the outcome that may change because of the IV.

Random assignment

Randomly placing participants into groups to reduce bias and create equal groups.

Case study

A detailed study of one person, group, or event to gather in-depth information.

Correlation

A relationship between two variables where changes in one are linked to changes in the other.

Positive correlation

Two variables increase or decrease together (both move in the same direction).

Negative correlation

One variable increases while the other decreases (move in opposite directions).

Meta-analysis

A study that combines results from many studies to find an overall conclusion.

Naturalistic observation

Observing behavior in a natural environment without interfering.

Hypothesis

A testable prediction about how two or more variables are related.

Falsifiable (hypotheses)

A hypothesis is falsifiable if it can be proven wrong by evidence or testing.

Operational definitions

Exact descriptions of how variables are measured or manipulated in a study.

Replication

Repeating a study to see if the results can be reproduced.

Central tendency

A single score that represents a set of data (mean, median, mode).

Variation

How spread out the data is; how much scores differ from each other.

Percentile rank

The percentage of scores in a distribution that are equal to or below a given score.

Mean

The average; add all values and divide by the number of values.

Median

The middle value in a set of ordered numbers.

Mode

The most frequently occurring value in a set of data.

Range

The difference between the highest and lowest score in a dataset.

Normal curve

A symmetrical, bell-shaped distribution where most scores are near the average.

Positive skew

A distribution where most scores are low and the tail stretches to the right (mean > median).

Negative skew

A distribution where most scores are high and the tail stretches to the left (mean < median).

Bimodal distribution

A distribution with two peaks (two values or ranges appear most often).

Standard deviation

A measure of how far scores typically are from the mean.

Regression toward the mean

The tendency for extreme scores/events to be followed by more average ones.

Sample

A smaller group selected from a population to represent it in a study.

Population

The entire group of people that researchers want to learn about.

Representative sample

A sample that accurately reflects the characteristics of the population.

Random sampling

Selecting participants randomly from a population so everyone has an equal chance to be chosen.

Convenience sampling

Selecting participants who are easiest to access, which can cause bias.

Generalizing

Applying results from a sample to the larger population.

Experimental group

The group in an experiment that receives the treatment or independent variable.

Control group

The group that does not receive the treatment; used for comparison.

Placebo

A fake treatment with no active effect, used to control for expectations.

Placebo effect

Changes in behavior or health due to belief in a treatment rather than the treatment itself.

Single-blind study

A study where participants do not know if they are in the experimental or control group.

Double-blind study

A study where neither participants nor researchers know who is in which group.

Experimenter bias

When a researcher's expectations influence the results or participants' behavior.

Social desirability bias

When participants respond in a way that makes them look good rather than being truthful.

Qualitative research/measures

Research that uses non-numerical data like descriptions, interviews, or observations.

Structured interviews

Interviews with a set list of questions asked in the same order to all participants.

Quantitative research/measures

Research that uses numerical data and statistics to measure variables.

Likert scales

A rating scale (ex: 1-5) used to measure opinions or attitudes.

Representation of participants

How well the participants reflect the diversity of the population being studied.

Peer review

The process where experts evaluate a study before it is published.

Replication (again)

Repeating a study to confirm its results and reliability.

Scatterplot

A graph showing points that represent the relationship between two variables.

Correlation coefficient (r)

A number from -1 to +1 that shows the strength and direction of a correlation.

Effect sizes

A statistical measure of how strong or meaningful the relationship/difference is.

Statistical significance

The likelihood that results happened due to the independent variable rather than chance.

Directionality problem

In correlation, not knowing which variable causes the other (A causes B or B causes A).

Third variable problem

In correlation, an outside factor may be causing both variables to change.

Institutional review (IRB)

A board that reviews research to make sure it is ethical and protects participants.

Informed consent

Participants must be told enough information to decide if they want to participate.

Informed assent

Agreement to participate given by someone not legally able to consent (like a child).

Protection from harm

Researchers must minimize physical and psychological risk to participants.

Confidentiality

Keeping participants' personal information and responses private.

Deception

When researchers mislead participants about the study to prevent biased behavior.

Debriefing

After the study, researchers explain the true purpose and any deception used.