Control & Extraneous Variables Flashcards
What are some methods of controlling extraneous variables?
Random allocation
Counterbalancing
Randomisation
Standardisation
What are extraneous variables?
Extraneous variables are any variable other than the IV that might affect the DV and thus affect the results.
What are confounding variables?
Something that varies systematically depending on the independent variable.
An EV that cannot be controlled, E.G…
Age, Gender
What are the types of extraneous variables?
Participant
Situational
Demand characteristics
Investigator effects
What are situational variables? Give examples.
Variables connected with the research situation & environment.
E.G.
Temperature, time of day, lighting, materials, etc.
How are situational variables controlled?
Using STANDARDISATION.
E.G. making sure that the temperature is
the same for both groups, the time of day is the same, etc.
What are participant variables? Give examples.
Variables connected with the research participants and their characteristics.
E.G.
age, intelligence, gender, etc.
How are participant variables controlled?
Using MATCHED PAIRS or RANDOM ALLOCATION.
To ensure participants with similar characteristics are allocated to different conditions which cancel out participant variables.
Random allocation reduces bias.
What is random allocation?
When researcher randomly assigns participants to a condition of the IV - greatly decreases chance that participant variables (E.G. mathematical ability) will affect the results.
What is counterbalancing?
Counterbalancing is a method used to reduce order effects in a repeated measures design when the sample is split in half with 1 half completing the 2 conditions in one order, and the other half completing the conditions in the reverse order. Any order effects are balanced out.
What does counterbalancing control for?
Order effects
Practice or fatigue effects.
What is randomisation?
When trials are presented in a random order to avoid any bias that the order of the trials might present.
What does randomisation, standardisation, random allocation and counterbalancing control for?
Randomisation - bias
Standardisation - situational variables
Random allocation - participant variables
Counterbalancing - order effects
What is standardisation?
Method of controlling situational variables by making procedures identical, ensuring every participant has the same experience, can establish a cause & effect link.
Makes the study replicable.
What are demand characteristics?
When pps guess the aim of research and change their behaviour to support/disrupt the research.
Pps act in a way to support/disrupt the hypothesis rather than behaving naturally, making the results lack validity.
