Extraneous Variables

• extraneous variables


  variables (other than the IV) that may have an effect on the DV. these do NOT vary systematically with the IV
• confounding variables


  variables (other than the IV) that will have an effect on the DV. these DO vary systematically with the IV. it provides an alternative explanation for your results. can't be controlled
• participant variables


  individual differences between participants that may effect the DV
• situational variables


  differences in the experimental conditions that may effect the DV
• demand characteristics


  any cues from the researcher/research situation that may indicate the purpose of the experiment, causes ppts. to change behaviour
• investigator effects


  effects of the investigator on the DV. this may be conscious or unconscious.
• randomisation


  use of chance to reduce the researcher's influence on the investigation. controls for investigator effects.
• standardisation


  using exactly the same formalised procedures and instructions for all participants in a research study. controls for situational variables.