AP Psych notes from 4.3 and onwards

Experiment

A research method in which an investigator manipulates one or more factors (independent variables) and observes the effect on the dependent variable.

Independent Variable

The factor that is changed or manipulated in an experiment, whose effect is being studied.

Dependent Variable

The outcome that is measured in an experiment, which may change when the independent variable is manipulated.

Confounding Variables

Other factors that can potentially influence the study's results, aside from the independent variable being studied.

Experimental Group

The group in an experiment that is exposed to the treatment or independent variable.

Random Assignment

The process of randomly assigning participants to different conditions to equalize the experimental and control groups.

Random Sampling

A method that creates a representative survey sample from a larger population.

Single Blind Procedure

An experimental procedure in which participants are unaware of whether they received the treatment or a placebo.

Double Blind Procedure

An experimental procedure in which neither the participants nor the researchers administering the treatment know which group is receiving the treatment.

Validity

The extent to which a test measures what it is supposed to measure.

Reliability

The extent to which findings can be replicated in research.

Placebo Effect

A phenomenon where participants experience changes in their condition simply because they believe they are receiving treatment.

Social Desirability

A bias that occurs when participants alter their responses to please the researcher.

Experimenter Bias

A form of bias that occurs when researchers unintentionally influence the results of an experiment to confirm their own beliefs.

Central Tendency

A statistical measure that identifies a single score as representative of an entire distribution of scores.

Mode

The most frequently occurring score in a data set.

Median

The middle score in a data set when the scores are arranged in order.

Mean

The average score in a data set, calculated by summing all scores and dividing by the number of scores.

Standard Deviation

A computed measure of how much scores vary around the mean score.

Normal Curve

A bell-shaped symmetrical curve that describes the distribution of many types of data, with most scores falling near the mean.

Descriptive Statistics

Numerical data used to describe characteristics of groups, including measures of central tendency and variation.

Inferential Statistics

Numerical data that allow one to generalize from sample data the probability of something being true of a population.

Null Hypothesis

The assumption that no difference exists between groups in a study.

Statistically Significant

A statistical statement indicating how likely it is that a result occurred by chance, assuming no difference exists between the populations being studied.

Effect Size

The strength of the relationship between two variables; a larger effect size indicates a stronger relationship.

Confidence Interval

A range of values that likely includes the population��s true mean value.