TYPE OF EXP AO1 & AO3 Flashcards
types of experimental methods
- Conditions under which an experiment is carried at:
Dependent on:
oHow much control we have over IV
o How much control we have over extraneous variables
o Decision betweenreliability OR validity
o Lab, field, quasi + natural
Lab experiments
- In environment that allows high degree of control over extraneous variables
- e.g. skinners box
- Controls variation of IV and measures change of DV
lab experiment ADVANTAGE
- More confident of relationship between IV + DV being casual
- High degree of control = method more easily reliable = method is reliable
lab experiment DISADVANTAGE
- High degree of control = situation is artificial = lack ecological validity (do not reflect natural behaviour)
- Lack mundane (everyday) realism
field experiments
- In real world setting
- Researcher still manipulates IV but little control over extraneous variables
- Pts don’t know they are taking part in experiment
Field experiments ADVANTAGE natural environment + demand characteristics
- More natural environment pp more comfortable therefore and behaviour is authentic results may be generalisable to everyday life
- Pp are unaware they’re being studied so less likely to show demand characteristics they’ll behave normally the study has greater external validity
Field experiment DISADVANTAGE more difficult control over CV/DV + Ethical issues
- more difficult control CV/EV, observed changes in the DV may be due to the IV, instead.
- It is difficult to establish cause and effect than in the lab
- There are ethical issues pp in a field experiment may not have given informed consent
Natural experiment
- the exp doesn’t manipulate the IV - it changed however not made by the exp
- someone or something else causes the IV to vary. (DV may be naturally occurring)
- E.G exam results
Natural exp ADVANTAGE maybe only practical / ethical option + greater external validity
- It may be unethical to manipulate IV e.g studying the institutionalsation of children
- Natural experiments involve real world such as the effects of a natural disaster on stress levels
Natural exp DISADVANTAGE the Natural event may occur rarely + pp are not randomly allocated
- many natural events are ‘one off’ and this reduces the opportunity for research
- The experimenter has no control over which pp are placed in which conditions
May results in CV e.g romanian orphans adopted early May be friendly ones
Quasi experiment
- when IV is an individual difference e.g. gender, intelligence may be naturally occuring
Quasi exp ADVANTAGE there is often high control + comparisons can be made
- Often carried out in controlled conditions and therefore shares some of the strengths of lab experiments this means it can be replicated
- In a quasi experiment the IV is a difference between people this means comparisons can be made
Quasi exp DISADVANTAGE pp arent randomly allocated
- exp has no control over which pp placed in which condition as the IV is pre-exsisting.
- Pp variables may have caused the change in DV acting as CV
- Researcher doesn’t manipulate IV cannot say change in DV was due to IV