Key Psychology Research Terms: Variables, Validity, and Bias

Independent Variable (IV)

The variable manipulated by the researcher to see its effect on the dependent variable.

Dependent Variable (DV)

The variable that is measured by the researcher.

Operationalisation

Making variables specific, objective, and measurable.

Aim

A general statement explaining the purpose of the study.

Hypothesis

A clear, testable prediction about the relationship between the IV and DV.

Directional Hypothesis

A hypothesis that predicts the direction of the effect of the IV on the DV.

Non-directional Hypothesis

A hypothesis that predicts a difference but not the direction of the effect.

Extraneous Variables

Any variables other than the IV that could affect the DV and confound results.

Situational Variables

Environmental factors that could affect participants' behaviour, such as noise or temperature.

Participant Variables

Individual differences between participants that could affect results, such as age or personality.

Investigator Effects

When the researcher's behaviour influences the participants' responses.

Demand Characteristics

Cues that make participants aware of the study's aim, changing their behaviour.

Randomisation

Using chance to reduce bias when selecting participants or assigning them to conditions.

Standardisation

Keeping procedures, instructions, and materials the same for all participants.

Reliability

The consistency of a study's results when repeated.

Validity

The extent to which a study measures what it claims to measure.

Internal Validity

The extent to which changes in the DV are caused by the IV.

External Validity

The extent to which findings can be generalised to other people or situations.

Sample Bias

When some groups are over- or underrepresented in a sample.

Generalisability

The extent to which findings apply to the wider target population.

Mundane Realism

How realistic the tasks and materials are compared to real life.