control

• Experimental controls


  Used in scientific experiments to prevent factors other than those being studied from affecting the outcome
• Experimental controls


  • They are needed to eliminate alternate explanations of experimental results
• Ways to control experiments

  • Randomisation
  • Counterbalancing
  • Standardisation
• Randomisation


  The deliberate avoidance of bias on the part of the researcher in order to keep the research as objective as possible
• Randomisation


  1. Participants are randomly assigned to one condition of the IV e.g. by selecting names at random out of a hat

  2. Random allocation to condition ensures that no bias has intruded over which participants take part in which condition

  3. If the procedure involves a list of words, digits or images presented to participants then the list must be decided randomly to avoid researcher bias
• Due to the nature of randomness one condition of the IV may result in a group of all female participants or a word list may have words beginning with the same letter appearing one after the other at the start of the list
• Counterbalancing


  Relevant to repeated measures designs and is implemented by splitting the participants in half, with one group completing the conditions in one order and the other group completing them in the reverse order
• Counterbalancing


  • Used to control for order effects (practice, fatigue, boredom)
• Standardisation


  The identical procedure set up in an experiment (or the questions used in self-report measures) across all conditions/participants
• Standardisation


  1. Instructions given to the participants

  2. Briefing prior to the procedure (including the consent form) and debriefing after the procedure has taken place

  3. Number of participants per condition

  4. Timings: each condition of the IV should run for the same amount of time

  5. Materials: identical materials must be used, the only exception being if the materials need to change for the IV to be implemented
• Standardisation


  • Allows the research to be replicated and reliable