Demand Characteristics, Pilot studies and Sampling

• what are demand characteristics?

  cues that might indicate the study's aim to p's. these cues can lead to p's changing their behaviours or responses based on what they think the research is about.
• why are demand characteristics problematic?

  they can bias research findings.
• what is social desirability bias?

  tendency to underreport socially undesirable attitudes & behaviours and to overreport more desirable attributes.
• what can social desirability cause?

  demand characteristics.
• what are investigator effects?

  researcher unintentionally affects & influences the outcome of the research they are conducting.
• what is a pilot study?

  small-scale study 'trial run' of a research design w/ a small no. of p's before the real study takes place. not results (aim) but methodology.

  • can help make sure instructions are clear.
  • measure is valid.
  • test isn't too boring/complicated.
  • try to prevent demand characteristics.
  • save money & time before carrying out proper study.
• what is a target population?

  all the people a psychologist wants to study.
• what is a sample?

  smaller group drawn from a target pop.

  • psychologists want their sample to be representative of their pop.
  • includes a good representation of characteristics, e.g. gender, age, IQ etc.
  • unrepresentative samples are biased which makes the data difficult to generalise.
• what is random sampling?

  every member of target pop. has an equal chance of being picked.
• what is a opportunity sample?

  researcher selects anyone who is willing & available to take part.
• what is stratified sampling?

  sub-groups (strata) which are proportional to the target pop.
• what is volunteer sampling?

  p's self-select to become part of study, volunteer when asked/respond to an advert.
• what is systematic sampling?

  'every nth person', uses a predetermined system to select p's from a target group.