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RESEARCH METHODS (1) exp (Sampling vol (Evaluation (Strength - unbiased,…
RESEARCH METHODS (1) 
Experimental Method
Aims & hypotheses
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Directional hypothesis states whether changes are greater or lesser, +ve or -ve etc.
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Control of Variables
Sources of bias
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Investigator effects = influence of researcher's behaviour on participants' behaviour e.g.. researcher may smile more at one group when recording how talkative they are, may encourage more chattiness
Controlling bias
Randomisation = use of chance when designing investigations to control for effects of bias e.g.. order of list of words randomly generated
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Experimental Design
2) Repeated Measures
The order in which participants tested should be varied to reduce order effects e.g.. practice effect or boredom
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Counterbalancing - To limit order effects counterbalancing often used - half participants do condition A then B & other half do condition B then A (ABBA technique)
3) Matched Pairs
Pairs of participants are matched & placed in separate groups eg. energy drink experiment - person who spoke most paired with person who spoke second most, one member of pair put in condition A & other in condition B.
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1) Independent Groups
Evaluation
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Limitation - participant variables may act at EVs e.g.. condition A could have more naturally talkative people than B
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Types of Experiment
Quasi-experiments
As IV a difference between people, participants can't be randomly allocated to experimental conditions because participants in each group decided before experimenter comes along
Evaluation
Strength - comparisons can be made regarding behaviours of different groups eg. people with & without autism
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Strength - often high control as carried out under controlled conditions, effects of EVs on the DV minimised
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IV is pre-existing condition, not a variable e.g.. age or gender
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Natural
DV may be assessed in natural environment or in lab e.g..Romanian Orphans the child's aggressive behaviour could be assessed in natural environment or lab
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Experimenter doesn't manipulate the IV e.g.. Romanian Orphans - IV was whether children adopted early or late & would have occurred anyway without experimenter
Field
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More natural environment, less controlled
Laboratory
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Sampling
4) Systematic Sample - system used, there is a pattern so every member of target pop does not have equal chance e.g.. every nth person chosen
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5) Stratified Sample - method to obtain representative sample e.g.. opinion poll (contains selection of subgroups selected according to their frequency in target population)
3) Random Sample - equal chance of selection for every member of target population e.g.. lottery or random number table
Evaluation
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Limitation - not perfect as can't reflect all the ways people are different within target population
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Populations - target population selected & sampling aims to obtain representative sample although often biased (certain groups like ages or gender over or under represented)
2) Volunteer Sample - ad on noticeboard or newspaper asking for participants so self-selecting unlike Opportunity
Evaluation
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Limitation - likely to be biased (volunteer bias - as volunteered likely to have certain characteristics not representative of target population)