RM: experimental design + types Flashcards
experimental design
the different ways in which the testing of participants can be organised in relation to the experimental conditions
independent groups
- 2 separate groups of ppts experience 2 separate conditions of experiment
- group 1 - control group
- group 2 - experimental group
- performance of 2 groups compared
what are the four TYPES of experiment
laboratory, field, Natural and Quasi
repeated measures
all ppts take part in all conditions of the experiment
- each ppt would experience control group condition + experimental group condition
AO3 for matched pairs
- ppts can never be matched exactly
- time consuming + expensive
- Strength = no order effects/ demand characteristics
matched pairs
- pairs of ppts first matched on some variables (I.e IQ)
- one member of the pair is assigned to condition A and other is assigned to condition B
AO3 for independent groups
- ppts who occupy different groups are not the same
- results may vary bc of individual differences (ppt variables) (controlled using random allocation)
- strength - order effects are not a problem
AO3 for repeated measures
- order effect problems - ppts repeat 2 tasks (create boredom/fatigue) (order = confounding variable)
- may work out study aim (Demand characteristics)
- Strength - fewer ppts needed
Field experiments
experiment takes place in a natural setting
- IV is manipulated in a natural more everyday setting
strengths of Laboratory experiments
- high control over extraneous variables - so can be sure that only IV is impacting DV (internal validity)
- replication is possible because of level of control
counterbalancing
- method for controlling order effects in repeated measures design
- 1/2 ppts experience conditions in one order + 1/2 in the opposite order
Limitations of Laboratory experiments
- may lack generalisability - conditions artificial
- ppts aware they are being tested - demand characteristics
-not representative of real life (Low mundane realism)
limitations of field experiments
- ethical issues - ppts unaware they are being studied so cant give consent
- loss of control of extraneous variables
Laboratory experiments
- conducted in highly controlled settings
- researcher manipulates IV
- researcher maintains control of extraneous variables
natural experiments
- researcher takes advantage of pre-existing IV
- called ‘Natural’ because variable would have changed even without researchers presence
strengths of field experiments
- high mundane realism - natural environment
- ppts unaware they are being studied - higher external validity
population
large group of people a researcher is interested in studying
- often called ‘target population’
sample
group who take part in a research investigation
- sample is drawn from target population
- representative of target population - generalisable
limitations of natural experiments
- natural occurring event is rare - difficult to generalise to other scenarios
- ppts not randomly allocated to experimental conditions
Quasi experiments
- IV is based on existing difference between ppl (i.e. gender, race)
- IV is not manipulated, it simply exists
strengths of quasi experiments
often carried out under controlled settings so same strengths as Laboratory experiments
Limitations of Quasi experiments
cannot randomly allocate ppts to conditions so may be confounding variables
strengths of Natural experiments
- high external validity - involve study of real life issues/problems as they happen
