Unit 0 Exam

Validity

The extent to which a test or experiment measures or predicts what it is supposed to.

Double-blind procedure

An experiment in which both participants and researchers are unaware of who has received the treatment or placebo, to prevent bias.

Placebo

An inactive substance or condition used in research to test the effectiveness of a treatment; participants may believe it works.

Experimental group

The group exposed to the treatment/independent variable.

Control group

The group not exposed to the treatment; provides a comparison baseline.

Theory

An explanation that organizes observations and predicts behaviors or events.

Hypothesis

A testable prediction often implied by a theory.

Operational definition

A carefully worded statement of exact procedures and measurements used in a study.

Overconfidence

The tendency to think we know more than we do and to overestimate accuracy.

Hindsight bias

The "I-knew-it-all-along" phenomenon; believing, after learning the outcome, that it could have been predicted.

Perceiving patterns in random events

Our eagerness to make sense of the world by finding order, even in random sequences.

Mean

The arithmetic average (add scores ÷ number of scores); best with symmetrical distributions.

Median

The middle score; best for skewed data.

Mode

The most frequently occurring score; best for categorical data.

Range

The difference between highest and lowest scores.

Standard deviation

A measure of how much scores vary around the mean; psychologists use it to see whether scores are packed together or spread out.

Sampling procedures (best practices)

Use random, representative samples to ensure findings can generalize to the population.

Naturalistic observation

Recording behavior in naturally occurring situations without manipulation.

Survey

Asking self-report questions to a representative, random sample of people.

Experiment

A research method in which one or more factors are manipulated to observe the effect on behavior or mental processes.

Causation vs. correlation

Correlation describes a relationship between variables but does not prove cause and effect. Only experiments can establish causation.

Correlation coefficient (r)

A statistical measure (-1 to +1) of the strength and direction of a relationship.

Positive correlation

Variables increase or decrease together.

Negative correlation

One variable increases as the other decreases.

Scatterplot

A graphed cluster of dots representing two variables, showing correlation strength and direction.

Illusory correlation

The perception of a relationship where none exists.

Normal curve

A bell-shaped distribution where most scores fall near the mean and fewer at the extremes; used to predict probabilities.

Scientific attitude

Curiosity (asking questions), skepticism (doubting until evidence), and humility (accepting mistakes and openness to new ideas).

Independent variable (IV)

The factor manipulated in an experiment.

Dependent variable (DV)

The outcome measured; the variable that may change in response to the IV.

Confounding variable

An outside factor other than the IV that might influence the DV.

Random sampling

Choosing participants randomly from a population to get a representative sample.

Random assignment

Randomly assigning participants to experimental or control groups to reduce pre-existing differences.

Statistical significance

A statement of how likely it is that a result occurred by chance; results are significant when the odds of chance are very low (p < 0.05).

Ethical guidelines for research (APA's 4)

Obtain informed consent, protect participants from harm/discomfort, keep information confidential, and debrief participants after the study.