What is an extraneous variable?
A variable other than the IV that may affect the DV if it is not controlled.
What is a confounding variable?
An extraneous variable that changes systematically with the IV and creates an alternative explanation for the findings.
What is the key difference between an extraneous and a confounding variable?
An extraneous variable may affect the DV, but a confounding variable also varies systematically with the IV.
What is a participant variable?
An individual difference between participants, such as age, intelligence, personality or motivation, that may affect the DV.
What is a situational variable?
A feature of the research environment or procedure, such as noise, temperature, time of day or instructions, that may affect the DV.
What are demand characteristics?
Cues in a study that allow participants to infer the aim and change their behaviour.
What are investigator effects?
Influences of the researcher’s behaviour or expectations on participants, procedures, data collection or interpretation.
What is randomisation?
Using chance to reduce systematic researcher bias in allocation, order or research materials.
What is standardisation?
Keeping relevant procedures, instructions and participant experiences consistent across a study.
Why is control of variables important?
It reduces alternative explanations, improves internal validity and supports more confident conclusions about the effect of the IV on the DV.