Experiments Flashcards
Strengths and weaknesses of field experiments
A: true to everyday life and high in ecological validity - more likely to act normal.
Less effort.
D: not controlled and lots of extraneous variables.
Reducing reliability because it’s not standardised and replicable.
Strengths and weaknesses of lab experiments
A: controlled environment minimises extraneous variables.
Reliable
D: Low ecological validity because may not reflect how people behave in everyday life so can’t be generalised to everyday scenario.
Participants might change the way they behave. (Demand characteristics).
More effort.
Strengths and weaknesses of Quasi experiments
A: high in ecological validity because they’re not manipulating the IV.
Helps us study variables we cannot manipulate.
D: difficult to conduct.
Can’t control some participant variables that may influence the results.
Strengths and weaknesses of repeated measures design
Same people in each condition
A: no participant variables (personality and persons life won’t effect results).
Only need to get half the people so it’s easier to collect sample.
D: the participants could change their behaviour if they work out what the study is about (demand characteristics).
Order effects- may get better or worse next time they do it as they’ve had practice.
Strengths and weaknesses of independent measures design.
Different people in each condition
A: no demand characteristics (because the participant won’t know what the opposite participant is doing so won’t be able to work out the aim of the procedure and change their behaviour.)
No order effect- no practice.
D: Extraneous variables - participant variables.
Double people needed- effort.
Strengths and weaknesses of matched participant design.
Using different people in each condition but making them as similar as possible on key characteristics. Done by testing individual on characterises, pairing them based on similar scores then placing one member of each pair into each group.
A: reducing participant variables.
No order effects or demand characteristics.
D: Can’t get rid of participant variables completely.
More effort.
How can participant variables be controlled?
Have same people in each condition - repeated measures design or extremely similar groups of people- matched participants design.
Use random sampling so participant variables are more likely to be evenly distributed.
How can order effects (situational variables) be controlled?
Having different people in each condition - independent measure design or matched participants design.
If repeated measures design used, this should be counter-balanced (participants split into 2 groups; group 1 doing condition A and group 2 doing condition B.)
How can environmental factors (situational variables) be controlled?
Impose controls on the experiment to ensure there are as few differences as possible between the two conditions e.g. same room, same temperature levels, same colour walls, same lighting.
How can demand characteristics (situational variables) be more controlled?
Don’t tell participant the aim of the experiment (single blind procedure).
Null hypothesis
The IV will have no significant effect on the DV. Any difference will be due to chance factors.
‘There will be no significant difference between… any difference will be due to chance factors’
Alternative hypothesis
The IV will significantly affect the DV
‘There will be a significant difference between…’
Two tailed hypothesis
The IV will affect the DV but no direction is given.
One tailed hypothesis
The IV will affect the DV in a certain direction.
Operationalisation
The process of making variables physically measurable or testable. This is done by recording some aspect of observable behaviour that is assumed to be indicative of the variable under consideration.
