Control of variables Flashcards
What are extraneous variables?
Any variables other than the IV that can affect the DV
What are confounding variables?
Any variables that are not controlled and therefore does affect the DV
Why must you control extraneous variables?
Because if not controlled, we don’t know whether the IV is causing the Dv or if the extraneous variable is, so we can’t establish cause and effect relationships.
What are the types of extraneous variables?
Situational variables- connected with research situation, e.g. temperature
Participant variables- individual differences, e.g. intelligence
What are demand characteristics?
Cues in the environment or inadvertently given by researcher which allow ppt to understand aims and hypotheses
Why are demand characteristics problematic?
They can bias research findings and reduce validity of results
What is the ‘Screw-you effect’?
Ppt attempts to discern experimenters hypotheses- Sabotage
What are investigator effects?
Investigator may unconsciously behave in such a way that their behaviour may influence the results of the study
What are two ways of controlling demand characteristics?
Single blind- Ppts don’t know hypotheses know which condition they’re in
Double blind- As above, but researchers don’t know which condition ppts are in
What is random allocation and how is it done?
Ppts assigned to conditions by chance
Number ppts, pick random number out of hat to assign to first condition, then another for second condition and so on until all assigned
What are the strengths of random allocation?
It eliminates investigator effects and bias
What is standardisation?
Using the same formalised procedures for all ppts, using standardised instructions, when ppts are given same instructions
What are the strengths of standardisation?
It allows for replicability and controls for experimenter effects
What is counterbalancing?
Half participants do condition A then B, others do B then A, used to combat order effects
