Research methods

• Experimental method: Aims

  Purpose of the investigation
• Experimental method: Hypotheses


  Testable, operationalised statement
• Experimental method: Directional or non-directional


  Identifying a difference/correlation or not. Choice depends on previous researches
• Variables: IV's and DV's

  IV manipulated, DV measured
• Variables: operationalised


  defining variables so they can be measured
• Research issues: extraneous variables


  nuisance variables but randomly distributed
• Research issues: confounding variables


  Vary systematically with IV
• Research issues: demand characteristics


  participants second guess the aims, alter their behaviour
• Research issues: investigator effects


  influence of researcher on DV/design decisions
• Research issues: randomisation


  chance methods to reduce bias
• Research issues: standardisation


  ensuring all participants have the same experience
• experimental designs: independant groups


  participants in each condition of experiment are different
• Independent groups evaluation


  Participant variables not controlled (use random allocation) less economical, no order effects
• experimental designs: repeated measures


  all participants take part in all conditions
• repeated measures evaluation


  order effects (use counterbalancing) demand characteristics. participant variables controlled. more economical
• experimental design: matched pairs


  similar participants paried on participant variables, allocated to A or B
• matched pairs evaluation: no order effects. cannot match exactly, time-consuming
• types of experiment: lab experiments


  IV is manipulated in a controlled setting. Participants go to researcher
• lab experiments evaluation

  high internal validity, replication more possible.

  
  

  However low internal validity and low external validity
• types of experiment: field experiments


  IV is manipulated in a natural setting. researcher goes to participant
• field experiments evaluation


  higher external validity (realism), lower internal validity (less control), ethical issues (consent not possible)
• types of experiment: natural experiment


  IV changed naturally. DV/setting may be natural or in a lab
• natural experiment evaluation


  only option for ethical reasons, high external validity. limited opportunities, low realism in labs,
• types of experiment: quasi-experiment


  IV based on existing difference between people, effect on DV is recorded
• quasi-experiment evaluation


  if in a lab issues as for lab experiment, no random allocation, no manipulation of IV
• population and sample: random sample


  equal chance of selection, lottery
• random sample evaluation


  potentially unbiased, time-consumign may not work
• population and sample: systematic sample


  selecting every nth person from list
• systematic sample evaluation


  objective method but time-consuming. those selected may refuse
• population and sample: stratified sample


  sample reflects the proportion of people in different population strata
• stratified sample evaluation


  representitive. cannot account for all subgroups
• population and sample: opportunity sample


  choosing whoever is available
• opportunity sample evaluation


  convenient. but unrepresentitive
• ethical issues: informed consent


  advise participants what is involved. reveals research aims
• volunteer sample evaluation


  Easy and participants engaged.

  Volunteer bias, responsive to cues
• population and sample: volunteer sample


  participants 'self-select
• how to deal w ethical issues: informed consent


  signed consent form
• ethical issues: deception


  misleading participants, witholding information. OK if not distressing
• how to deal w ethical issues: deception


  debriefing, right to withdrawl data,
• ethical issues: protection from harm


  psychological or physical risk