Research Methods Specialist Terminology

Independent variable (IV)

The variable that is manipulated by the researcher (or changes naturally in non-lab experiments). It is manipulated in order to measure its effects on a dependent variable.

Dependent variable (DV)

The variable that is measured by the researcher. Any effect on the DV should be caused by the changes in the IV and not due to extraneous variables.

Operationalisation

Refers to ensuring variables are specific and measurable. Important in psychology when testing broad concepts like memory, e.g. 'number of items accurately recalled in 30 seconds.'

Aim

A general statement on the purpose of the study. Based on a question raised from previous research or theory.

Hypothesis

A precise, testable statement that predicts the expected outcome of the study. Must refer to a clearly operationalised IV and DV.

Directional hypothesis

States the 'direction' of the impact of the IV on the DV and predicts the nature of this effect. Made when a theory or findings of previous research suggest a particular outcome.

Non-directional hypothesis

Does not state the 'direction' of the impact of the IV on the DV, only that there will be a difference between the conditions of the IV. Appropriate when there is no theory or previous research to make a prediction from.

Extraneous variables

Any variables in a study (except the IV) that could potentially affect the DV and therefore confound (confuse) the results. Can be split into situational and participant variables.

Situational variables

Any features of the experimental environment that may affect the results of an experiment, e.g. temperature of a room, time of day, noise, location, etc.

Participant variables

Any individual differences between participants that may affect the results of an experiment, e.g. personality, age, gender, intelligence, motivation, etc.

Investigator effects

Any impact of a researcher's behaviour (including unconsciously) on the outcome of results. They may expect a certain response from participants depending on conditions, and act differently towards them.

Demand characteristics

Any cue from the researcher or situation that participants may interpret as revealing the purpose of an investigation. May cause participants to change behaviour deliberately or unconsciously.

Randomisation

The use of chance in setting up an investigation to reduce investigator effects and participant variables. Can be used when selecting participants, assigning them to conditions, generating word/number lists, etc.

Standardisation

Ensuring that all procedures/materials/instructions within an investigation are kept the same for all participants. Helps reduce the impact of investigator effects or situational variables.

Reliability

Refers to consistency of measurements: tests/observations in a study must be standardised so that everyone gets similar results. Procedures should be easily replicable.

Validity

The extent to which a study's findings are accurate and actually measuring what they claim to measure. Results may not be true representations of behaviour if affected by confounding variables.

Internal validity

The extent to which we are testing what we actually intended to test within a study. Results may be influenced by demand characteristics, investigator effects, or confounding variables.

External validity

The extent to which a study's findings can be generalised/applied to other situations or contexts. May be reduced if there is sample bias in the study.

Sample bias

When certain groups are over- or under-represented in a sample compared to their representation in the wider population, e.g. using only one gender or culture.

Generalisability

Refers to applying results from a study to the wider target population. Based on the assumption that findings from the original sample are the same for everyone else in the target population.

Mundane realism

Refers to whether the materials and procedures in an experiment are similar to events that occur in real life. For example, recalling faces of classmates has more mundane realism than recalling a random word list.