Research Methods Full Set

The first affected family member who seeks medical or psychological attention, often used in genetic studies.

Proband

A method involving the analysis of verbal reports to understand cognitive processes.

Protocol Analysis

A qualitative research approach conducted in natural settings without manipulating variables.

Naturalistic Inquiry

A statistical test that looks for an effect in one direction.

One-Tailed Test

A statistical test that checks for effects in both directions.

Two-Tailed Test

Factors like history, maturation, testing, instrumentation, and selection that can bias results.

Threats to Internal Validity

Rejecting a true null hypothesis, leading to a false positive.

Type I Error

Failing to reject a false null hypothesis, leading to a false negative.

Type II Error

Correctly rejecting the null hypothesis for the wrong reason or interpreting results incorrectly.

Type III Error

External Validity

The extent to which findings can be generalized to other settings, people, or times.

Internal Validity

The degree to which observed effects can be attributed to the independent variable, not other factors.

Reliability

The consistency or repeatability of a measure.

Validity

The degree to which a test measures what it claims to measure.

The process of developing a test including defining the purpose, item writing, pilot testing, and standardization.

Test Construction

A statistic that measures inter-rater agreement for categorical items, correcting for chance agreement.

Kappa Coefficient

A measure of internal consistency reliability for dichotomous items (e.g., KR-20, KR-21).

Kuder-Richardson Formula

In item response theory, shows the probability of a correct response as a function of ability.

Item Characteristic Curve (ICC)

The proportion of test-takers who answer an item correctly; lower values indicate harder items.

Item Difficulty

A theory of test scoring that considers the difficulty and discriminatory power of items.

Item Response Theory (IRT)

Assessments where scores are interpreted relative to a normative sample.

Norm-Referenced Tests

Assessments where performance is measured against a fixed set of criteria.

Criterion-Referenced Tests

The predictor is the variable used to forecast another (criterion) variable.

Predictor/Criterion

A standard score with a mean of 50 and a standard deviation of 10.

T-Score

A statistical adjustment to account for the probability of guessing answers correctly on multiple-choice tests.

Correction for Guessing

A technique to assess construct validity using multiple traits and methods.

Multitrait-Multimethod Matrix (MTMM)

A single-subject experimental design that includes a baseline period (A), a treatment period (B), a return to baseline (A), and a second treatment (B) to establish treatment effects.

ABAB Design

A method to control for order effects in repeated measures designs by varying the order of conditions across participants.

Counterbalanced Design

Neither the participants nor the experimenters know who is receiving the treatment to reduce bias.

Double-Blind Design

A quasi-experimental design measuring a single group repeatedly before and after a treatment/intervention.

Interrupted Time-Series Design

A design used to control for order and sequence effects in repeated measures with multiple treatments.

Latin Square Design

Participants are matched on certain variables to control for confounding factors before being assigned to groups.

Matched Subject Design

A single-subject design where treatment is introduced at different times across behaviors, settings, or subjects.

Multiple Baseline Design

A research design that focuses on the responses of a single participant.

Single-Subject Design

A true experimental design that controls for pretesting effects by using four groups with varying exposure to pretests and treatments.

Solomon Four-Group Design

Statistical data used for prediction based on group-level data, often in risk assessment.

Actuarial Data

A statistical method used to compare means among three or more groups.

ANOVA (Analysis of Variance)

The weakening of the observed correlation due to measurement error.

Attenuation

Correlation of a variable with itself over successive time intervals, common in time-series data.

Autocorrelation

States that the sampling distribution of the mean approaches a normal distribution as the sample size increases.

Central Limit Theorem

A non-parametric test used to determine if a relationship exists between categorical variables.

Chi-Square

Indicates the proportion of variance in the dependent variable explained by the independent variable(s).

Coefficient of Determination (R²)

A range of values within which a population parameter is likely to fall with a certain level of confidence.

Confidence Interval

A statistical measure of the strength and direction of a linear relationship between two variables.

Correlation

A regression analysis used when the dependent variable is categorical (often binary).

Logistic Regression

A statistical technique that uses multiple predictors to estimate the value of a criterion variable.

Multiple Regression

A weighted average of variances from different groups, used in t-tests when variances are assumed equal.

Pooled Variance

The standard deviation of a sampling distribution, measuring the precision of a sample estimate.

Standard Error

Indicates how many standard deviations a score is from the mean.

Standard Score (Z-Score)

The probability that an observed effect is not due to chance (commonly p < .05).

Statistical Significance

A statistical test used to compare the means of two groups.

T-Test

A measure of how much scores differ from the mean.

Variance

The extent to which scores differ from each other and the mean (includes range, variance, standard deviation).

Variability

Values that do not change within a given context.

Constants

Characteristics or conditions that can take on different values.

Variables

A variable that affects the strength or direction of the relationship between independent and dependent variables.

Moderating Variable

A variable that explains the mechanism through which the independent variable affects the dependent variable.

Mediating Variable

Variables that have two categories.

Dichotomous Variables

Variables that have a range of numeric values.

Continuous Variables

A sampling method where groups (clusters) are randomly selected, not individuals.

Cluster Sampling

Allocating participants to different groups purely by chance to control for confounding variables.

Random Assignment

The difference between sample statistics and the actual population parameters.

Sampling Error

The number of participants or observations included in a study.

Sample Size

Cues that inform participants of the expected outcome, potentially biasing their behavior.

Demand Characteristics

A summary of how often different scores occur in a dataset.

Frequency Distribution

The percentage of scores below a particular value.

Percentile Rank

Methods like factor analysis or principal components analysis used to reduce large datasets into key variables.

Data Reduction Techniques

A statistical procedure that combines results from multiple studies to determine overall trends.

Meta-Analysis

A method of fitting regression models by adding or removing predictors based on statistical criteria.

Stepwise Multiple Regression

A multivariate technique that tests theoretical models involving multiple variables and relationships.

Structural Equation Modeling (SEM)

A method for analyzing patterns in data over time.

Trend Analysis

A statistical method used to identify underlying factors or constructs within a set of observed variables.

Factor Analysis

In factor analysis, indicates how much variance a factor explains.

Eigenvalue