AP Psychology: Research Design, Ethics, and Statistical Reasoning

Random assignment

An experimental technique that helps to lessen the amount of preexisting differences between two groups.

Single-blind procedure

An experimental procedure in which the participants are uninformed or blind about the treatment or placebo that they are receiving.

Double-blind procedure

An experimental procedure in which neither the participants nor the research staff know whether the participants received a treatment or placebo.

Confounding variable

Factors other than the factor being studied that could possibly influence the study's results.

Operational definition

A statement that specifies the procedures that are manipulating the independent variable and the measure of the dependent variable.

Validity

A goal of experimental design referring to the extent to which a test or experiment measures or predicts what it is supposed to.

Quantitative research

A research method that relies on quantifiable, numerical data to represent degrees of a variable (e.g., using a Likert scale).

Qualitative research

A research method that relies on in-depth, narrative data that are not translated into numbers (e.g., using a structured interview).

Confederates

People in scientific research who pretend to be fellow participants but are actually part of the experiment.

APA Ethical Rules

Four major ethical rules supported by the American Psychological Association: 1) obtain potential participants' informed consent (or informed assent for minors), 2) protect participants from greater-than-usual harm and discomfort, 3) keep information about individual participants confidential, and 4) fully debrief people.

Histogram

A type of bar graph that depicts a frequency distribution.

Mode

The score that is most frequently occurring in a distribution.

Mean

The arithmetic average of a distribution, obtained by adding the scores and then dividing by the total number of scores.

Median

The middle score in a distribution; half the scores are above it and half are below it.

Skewed distribution

A representation of scores that lack symmetry around their average value, causing the distribution to be lopsided.

Range

A measure of variation calculated as the difference between the lowest and highest scores.

Standard deviation

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

Normal curve

A symmetrical, bell-shaped distribution that applies to large numbers of data; on a Wechsler IQ test, about $68\%$ of people score within $\pm 15$ points of $$100