Research methods : EXPERIMENTS + DESIGN

• Laboratory experiment main features : the independent variable is manipulated, the depend variable is measured and any extraneous variable should be controlled
• The aim of a lab experiment is to establish the cause and effect relationship between the manipulation of the IV and the changes in the Dv
• Extraneous Variables include : participant variables -->age , gender , intelligence. Situational variables —> experimental setting , temperature , lighting . Experimenter variables —> personality , appearance and conduct of the researcher
• Extraneous variables : could impact the dependent variable
• Confounding variable : has impacted the dependent variable
• Operationalisation : defining the variables precisely —> exactly how the IV will be manipulated and how the DV will be measured
• Advantages of laboratory experiments : high levels of control over all of the variables in the experiment . The use of standardised procedures means that the research is replicable which increases reliability
• Disadvantages of laboratory experiments : demand characteristics may be an issue . lack of ecological validity due to artificial nature of the procedure . Lack mundane realism —> this means results cannot be generalised to real world behaviours
• Field Experiments : Independent variable is manipulated .The dependent variable is measured. In the participants natural environment .
• Advantages of field experiments : High ecological validity due to being in a real life setting . Participants are less likely to show demand characteristics due to being less likely to know what is expected from them . high levels of mundane realism.
• Disadvantages of field experiments: harder to control extraneous variables —> could change the measurement of the dependent variable. Harder to replicate due to being in a natural environment
• Natural experiments : Naturally occuring changes in the independent variable are observed and recorded. dependent variable is measured . In the participant natural environment
• Advantages of natural experiments : Highest level of ecological validity due to being in a natural setting with natural behaviour . Less bias from sampling or demand characteristics.
• Disadvantages of natural experiments : Lack of control over outside variables . Replicable issues which affect reliability.
• Quasi Experiments : Independent variable cannot be manipulated , E.g age or gender . dependent variable is measured . A natural experiment is a subtype of quasi experiments however quasi can also take place in a lab .
• Advantages of quasi experiments : high external validity —> quasi experiments research design tend to be more real world application , especially within social sciences. Often carried out in controlled conditions —> High control , better replication. Avoids ethical issues surrounding the manipulation of the independent variable
• Disadvantages of quasi experiments : confounding variables —> cannot use random allocation to condition . Difficult to explain a cause and effect conclusion due to participants being aware they are being studied .
• Experimental design are the ways participants are allocated to experimental groups Of an investigation .
• Repeated measure design : Where the same participants are allocated to all groups of an experiment.
• Advantages of repeated measure design : The result will avoid participant variables due to using the same participants in all the groups . No need for extra participants so lowers costs
• Disadvantages of repeated measures design : Risk of observing order effect ( e.g practice/fatigue effect) however risk can be reduced by counterbalancing . If a participant drops out , data will be lost in all conditions
• Independent groups design : where different participants take part in each experimental conditions ( allocated randomly) .
• Advantages of independent group design : order effect cannot be observed due to not using the same participants . Data collection will be less time consuming if all conditions of the experiment can be conducted simultaneously.
• disadvantages of independent group design : different participants need to be recruited for each condition which can be difficult and expensive . Risk of participant variables e.g individual differences .
• Matched Pairs design : where participants take part in only 1 experimental condition but are recruited to have similar characteristics to other participants in other conditions
• Advantages of matched pairs design : order effect won’t be observed . Reduced risk of participants variables .
• Disadvantages of matched pairs design : different participants need to be recruited for each condition which can be difficult and expensive . Very difficult to match participants identically.
• minimising the effect of extraneous variables : standardisation , counterbalancing , randomisation .
• Standardisation ensures all extraneous variables are kept the same across conditions . ( keeps the methods and procedures the same )
• counterbalancing is used in repeat measures design to prevent order effect influencing the results .
• Process of counterbalancing : split participants into 2 groups . 1 group does condition A then B . Other group will do condition B then A . Allows the order effect impacting on both condition equally