Experimental method

• Aims

  • General statements that describe the purpose of the investigation.
  • Developed from theories
  • E.g To investigate whether drinking energy drinks makes people more talkative.
• Hypotheses

  • Clear, precise, testable statement that states the relationship between the variables being investigated.
• What words should a directional hypothesis include?

  More or less, higher or lower.
• Directional hypothesis

  • States the direction of the difference or relationship.
• Non-directional hypothesis

  • Does not state the direction of difference or relationship.
• How do you know which type of hypothesis to use?

  • Researchers use a directional hypothesis when a theory or findings of previous research suggests a particular outcome.
  • When there is no theory or previous research, researchers use a non-directional hypothesis.
• What key things need to be included in a hypothesis?

  1. IV and DV are clear and measurable.
  2. You have stated the relationship between the IV and DV.
  3. Directional or non-directional.
• Independent variables


  Some aspect of the experimental situation that is manipulated by the researcher.
• Dependent variable


  Variable that is measured by the researcher. Any effect on the DV should be caused by the IV.
• Operationalisation

  • Clearly defining variables in terms of how they can be measured.