PSY 203 Introduction to Research Methods in Psychology Exam 3 Terms & Definitions

A comprehensive set of flashcards covering key terms and definitions for Chapters 2, 4-6, 8-9, & 12 in PSY 203.

Dependent variable

What the experimenter measures or records; value depends on level of independent variable.

Independent variable

What the experimenter manipulates; must have at least 2 levels; suspected cause of an effect.

Observed score

Components true score, systematic error, and random error.

True score

Measure obtained by independent and different procedures free from error.

Measurement bias

Nonrandom error in one direction.

Systematic error

Influence that acts on the response or measure in the same direction and by the same amount.

Random error

Influence that acts on the response variable by different amounts and could be in different directions.

Accuracy

Degree to which observed value matches true value.

Face Validity

Content of the test is appropriate.

Criterion-Related Validity

Test score predicts future behavior (predictive validity) and test scores correlated with current behavior (concurrent validity).

Descriptive statistics

Use data to describe population in graphs and summary statistics.

Mean

The middle (or average) of the dataset that is affected by extreme values.

Median

The unbiased middle of the dataset once the values are ordered from smallest to largest.

Mode

The most frequent value in the dataset.

Standard deviation

Measure of variation around mean either above or below the mean.

Normal distribution

Function that represents distribution of many random variables as a symmetrical bell-shaped graph.

Outlier

Infrequent observations; data points that do not follow characteristic distribution of remaining data.

Nominal scale

Category information.

Ordinal scale

Category and rank order information.

Interval scale

Category and rank order information and equidistance.

Ratio scale

Category and rank order information, equidistance, and true zero.

Null hypothesis

Hypothesis that there is no effect of the treatment.

Alternative hypothesis

Hypothesis that there is an effect of the treatment.

Alpha level

A fixed probability of rejecting the null hypothesis of no effect when it is in fact true.

Effect size

Measures of the magnitude or meaningfulness of a relationship between two variables.

Independent samples t-test

Used to test hypotheses about population mean when sample size is intermediate with a normal distribution and participants belong to two different groups.

Double-blind control

Procedure in which participants and experimenters are unaware of the experimental conditions.

Placebo effects

Tendency to report improvement/treatment is effective because expect that.

Subject variable

An experience or characteristic of a research participant that may influence study results.

Quasi-experiments

Research design with at least one non-manipulated variable.

Cohort effect

Any outcome associated with being a member of a group whose members all undergo similar experiences.