Concept

Constructs

Nominal (Categorical) Scale

Ordinal (Rank) Scale

Interval and Ratio Scales

Hypothesis

Operationalisation of a Hypothesis

Reliability

Reliability Coefficient

Test-retest

Parallel-form

Inter-rater

Split-half

Internal Consistency (Cronbach Alpha)

Validity

Measurement Validity

Internal Validity

External Validity

Ecological Validity

Face Validity

Content Validity

Construct Validity

Convergent Validity

Discriminant Validity

Measurement Error

Between-subjects Design

Within-subjects Design

Mixed Design

Quasi-experimental Design

Correlation Research

Field Observation

Questionnaire Surveys

Secondary Data Analysis

Biased Sample

The Third Variable Problem

Experimental Research

Selection Bias
(internal validity)

Regression to the Mean
(internal validity)

Maturation
(internal validity)

History
(internal validity)

Testing
(internal validity)

Mortality
(internal validity)

Instrument Change
(internal validity)

Experimenter Bias
(internal validity)

Representative Sample of Participants
(external validity)

Representative Sample of X's and Y's
(external validity)

Representative Sample of Situations
(external validity)