Psychology Unit 0 Key Terms

critical thinking

Looking at evidence and reasoning before accepting a claim.

hindsight bias

Believing after something happens that you knew it would happen.

peer reviewers

Experts who check research before it is published.

theory

An explanation that organizes observations and predicts behavior.

hypothesis

A testable prediction about a relationship between variables.

operational definition

A specific way a variable is measured or defined.

replication

Repeating a study to see if the results happen again.

case study

A detailed study of one person or small group.

naturalistic observation

Watching behavior in its natural setting without interfering.

survey

A method of collecting information by asking people questions.

social desirability bias

Giving answers that make you look more socially acceptable.

self-report bias

Providing inaccurate information about yourself.

sampling bias

When a sample does not accurately represent the population.

random sample

A sample where everyone has an equal chance of being chosen.

population

The entire group being studied.

correlation

A relationship between two variables.

correlation coefficient

A number from -1.00 to +1.00 showing the strength and direction of a correlation.

variable

Anything that can change or vary in a study.

scatterplot

A graph showing the relationship between two variables.

illusory correlation

Seeing a relationship between variables when one does not really exist.

regression toward the mean

Extreme results tend to become closer to average when measured again.

experiment

A study where researchers change one variable and measure its effect.

experimental group

The group that receives the treatment.

control group

The group that does not receive the treatment.

random assignment

Assigning participants to groups by chance.

single-blind procedure

Participants do not know which group they are in.

double-blind procedure

Neither participants nor researchers know who gets the treatment.

placebo effect

Changes caused by expectations rather than the actual treatment.

independent variable

The variable the researcher changes.

confounding variable

An outside variable that could affect the results.

experimenter bias

When a researcher's expectations affect the results.

dependent variable

The variable being measured in an experiment.

validity

How accurately a study or test measures what it is supposed to measure.

quantitative research

Research using numerical data.

qualitative research

Research using descriptions and non-numerical data.

informed consent

Participants agree to a study after being told important information about it.

debriefing

Explaining the true purpose of a study to participants afterward.

descriptive statistics

Numbers used to summarize and describe data.

histogram

A graph showing how often numerical scores occur.

mode

The most common score.

mean

The average score.

median

The middle score.

percentile rank

The percentage of scores below a particular score.

skewed distribution

A distribution with more scores toward one side.

range

The difference between the highest and lowest scores.

standard deviation

A measure of how spread out scores are from the mean.

normal curve

A bell-shaped distribution where most scores are near the mean.

inferential statistics

Statistics used to draw conclusions about a larger population.

meta-analysis

Combining results from many studies to find an overall result.

statistical significance

A result unlikely to have happened by chance.

effect size

A measure of how large or strong a result is.