Lesson 2: Control of variables

• What are extraneous variables?

  Other variables affecting results besides IV and DV
• Why must extraneous variables be controlled?

  They can affect the DV if uncontrolled
• How are extraneous variables identified in a study?

  At the start of the study by the researcher
• What are the methods to minimize extraneous variables?

  1. Standardisation

  • Ensure same conditions for all participants
  • Reduces variation across conditions

  1. Randomisation

  • Use chance methods to control bias
  • Reduces investigator effects
• What is the purpose of standardisation in research?

  To ensure participants experience the same conditions
• How does standardisation reduce the effect of extraneous variables?

  By minimizing variation in factors across conditions
• What is randomisation in research?

  Use of chance methods to control for bias
• How can randomisation be implemented in a study?

  By drawing names from a hat
• Why is randomisation important in research?

  It reduces investigator effects on results
• What happens if extraneous variables become confounding variables?

  They confuse results affecting the DV
• What are situational variables in research?

  Aspects of the environment affecting results
• How can the investigator effect impact results?

  By paying more attention to some participants
• What are the methods to minimize situational variables?

  1. Double blind procedures

  • Neither participants nor experimenters know conditions

  1. Single blind procedures

  • Participants are unaware of their condition
• What are participant variables?

  Characteristics of participants affecting results
• What are demand characteristics?

  Clues that lead participants to change behavior
• What is participant reactivity?

  Tendency to react to cues from the environment
• What are the methods to minimize participant variables?

  1. Random allocation

  • Ensures even spread of characteristics

  1. Counterbalancing

  • Controls for order effects in repeated measures
• What is random allocation in research?

  Ensures each participant has equal chance
• What is counterbalancing used for?

  To control for order effects in repeated measures
• What does counterbalancing involve?

  Half participants do conditions in one order