Controlling variables

• Randomisation

  The use of chance to control the effect of bias when designing research and order of experimental conditions

  
  

  The element of chance reduces/minimises investigator effects/bias

  
  

  
  
• Standardised procedures

  All participants are given the same procedure and instructions in the research study

  Ensures researcher that extraneous variables are controlled
• Single blind procedure

  Where participants are unaware of the research's aim or the condition they are allocated

  This is done to reduce demand characteristics
• Double blind procedure

  Where neither the participants or researcher is aware of the aims of the study

  This is to reduce investigator effects and demand characteristics