what are the 4 experimental methods
- laboratory
- field
- natural
- quasi
what is a lab experiment
- controlled environment → less EV
- manipulates IV to measure effect on DV
- ppts aware → unlike real life
strength of lab experiments
high control of EV → internal validity →conclusions about cause and effect can be drawn
limitation of lab experiments
low external validity → artificial nature → low eco validity →findings not generalisable to other settings + demand characteristics
what is a field experiment
- carried out in natural conditions
- manipulates IV to measure effect on DV
- ppts dont know theyre taking part
strength of field experiments + However point
high ecological validity → representative of everyday life HOWEVER less control over EV → can become confounding variables → distort findings → cant draw cause and effect relationship
limitation of field experiments
ethical issues → ppts didnt give full informed consent → needs to conduct cost benefit analysis
what is a natural experiment
- doesnt manipulate the IV
- examines effect of existing IV on the DV
- IV is naturally occurring (flood, earthquake)
strength of natural experiment + HOWEVER point (ext validity)
high level of external validity → high ecological validity → real life issues are studies rather than manipulated artificially HOWEVER, no control over EV → difficult to assess effect of IV on the DV → hard to draw cause and effect relationship
strength of natural experiment + HOWEVER point (insights gained)
insights gained into real life situations HOWEVER , only occurs rarely → low generalisability
what is a quasi experiment
- naturally occurring IV, but one which already exists
- the IV is a differende between people (age, gender)
- examine the effect of IV on the DV
- can be conducted in natural OR lab setting
limitation of quasi experiments ( random allocation)
ppts cant be randomly allocated → bias → IV to which they belong is predecided → less certain that the IV alone will have caused the effect on the DV as other dispositional factors couldve played a role
limitation of quasi experiments (methodological issues)
when in natural conditions → no control over EV AND when in lab conditions → high level of control means low ecological validity → low generalisability
