experimental method

• Aims

  • A general expression of what the researcher intends to investigate
• operationalised hypothesis

  • A statement of what the researcher believes to be true.
  • It should be operationalised = clearly defined and measurable.
  • Directional hypothesis = states whether changes are greater or lesser, positive or negative, etc.
  • Non-directional hypothesis = doesn't state the direction, just that there is a difference, correlation, association
• independent/dependent variables

  • Researcher causes the independent variable (IV) to vary records the effect of the IV on the dependent variable (DV)
• extraneous variables

  • 'nuisance variables that "muddy the water' and may make it more difficult to detect an effect
  • A researcher may control some of these.
• Confounding variables

  • Change systematically with the IV so we cannot be sure if any observed change in the DV is due to the CV or the IV
  • cant be controlled
• demand characteristics

  • Refers to any cue from the researcher or research situation that may reveal the aim of the study, and change participants' behaviour.
• investigator effects

  • Any effect of the investigator's behaviour on the outcome of the research (the DV) and also on design decisions.
• randomisation

  • The use of chance when designing investigations to control for the effects of bias
  • Eg = allocating participants to conditions
• standardisation

  • Using exactly the same formalised procedures for all participants in a research study, otherwise differences become EVs.
• Pilot studies

  • Small-scale trial run of an investigation to ‘road-test' procedures, so that research design can be modified
• control groups/conditions

  • Control groups (independent groups design) or control conditions (repeated measures design) are used to set comparison
  • They act as a ‘baseline’ and help establish causation
• single blind

  • A participant doesn't know the aims of the study so that demand characteristics are reduced
• double blind

  • Both participant and researcher don't know the aims of the study to reduce demand characteristics and investigator effects