Research Methods Rapid Review for AP Psychology (page 2)

A more in-depth study guide for this review can be found at:

• Experimental and Correlational Research Methods for AP Psychology
• Elementary Statistics for AP Psychology

Theories—organized sets of concepts that explain phenomena.

Hypothesis—prediction of how two or more factors are likely to be related.

Replication—repetition of the methods used in a previous experiment to see whether the same methods will yield the same results.

Independent variable (IV)—the factor the researcher manipulates in a controlled experiment (the cause).

Dependent variable (DV)—the behavior or mental process that is measured in an experiment or quasi-experiment (the effect).

Population—all of the individuals in the group to which the study applies.

Sample—the subgroup of the population that participates in the study.

Random selection—choosing of members of a population so that every individual has an equal chance of being chosen.

Experimental group—the subgroup of the sample that receives the treatment or independent variable.

Control group—the comparison group; the subgroup of the sample that is similar to the experimental group in every way except for the presence of the independent variable.

Random assignment—division of the sample into groups so that every individual has an equal chance of being put in any group or condition.

Confounding variables—factors that cause differences between the experimental group and the control group other than the independent variable.

Operational definition—a description of the specific procedure used to determine the presence of a variable.

Experimenter bias—a phenomenon that occurs when a researcher's expectations or preferences about the outcome of a study influence the results obtained.

Demand characteristics—clues participants discover about the purpose of the study that suggest how they should respond.

Single-blind procedure—research design in which participants don't know whether they are in the experimental or control group.

Double-blind procedure—research design in which neither the experimenter nor the participants know who is in the experimental group and who is in the control group.

Placebo—a physical or psychological treatment given to the control group that resembles the treatment given to the experimental group, but contains no active ingredient.

Placebo effect—a response to the belief that the independent variable will have an effect, rather than the actual effect of the independent variable, which can be a confounding variable.

Reliability—consistency or repeatability of results.

Validity—the extent to which an instrument measures or predicts what it is supposed to measure or predict.

Statistics—a field that involves the analysis of numerical data about representative samples of populations.

• Descriptive statistics—numbers that summarize a set of research data obtained from a sample.
• Frequency distribution—an orderly arrangement of scores indicating the frequency of each score or group of scores.
• Central tendency—average or most typical scores of a set of research data or distribution.