Experiments- Method, Control of Variables, Design, Types

Method
1. Aims
  1. General statement describing the purpose of the experiment
2. Hypotheses
  1. Testable statement on the relationship between the variables
    1. Based on theory
  2. Directional
    1. Clarifying the type of difference between the two conditions
      1. Drinking energy drinks increases your talkativeness
    2. Used when previous research suggests particular outcome
  3. Non-directional
    1. Stating that there will be a difference between the conditions, but not the type
      1. Drinking energy drinks affects your talkativeness
    2. Used when there is no previous research into the area
3. Variables
  1. Independent Variable
    1. Aspect of the experiment which is manipulated/changed
  2. Dependent Variable
    1. Measured the record effect of changing the IV
  3. The hypothesis should state the IV and DV
    1. E.g. The group who drink energy drinks will be more talkative than the group who drink water
      1. IV= type of food
      2. DV= IQ
  4. Operationalisation
    1. Making the variables measurable
      1. E.g. the group who drink 200ml of energy drink will say more words in 10 minutes than the group who drink 200ml of water
Control of variables
1. Extraneous variables
  1. Unwanted variables, other than the IV, which may influence the DV
  2. E.g. gender, lighting in room, age
  3. Don't vary systematically with the IV
2. Confounding variables
  1. Unwanted variable, other than the IV, which may have influenced the DV
  2. Unsure of true source of changes in DV
  3. Vary systematically with the IV
  4. E.g. personality
3. Demand characteristics
  1. Guessing the aim of an experiment and reacting accordingly
  2. Act in a way which they think is 'expected' or over-perform to please
  3. Under-perform to sabotage results
  4. Unnatural behaviour
4. Investigator effects
  1. Researcher favouring certain participants
  2. Unconscious clues
  3. Selection of materials, participants, instructions etc.
  4. Leading questions
5. Randomisation
  1. Reduces effects of EV/CVs and investigator effects
    1. Random generation
    2. Order of conditions randomly determined
6. Standardisation
  1. Same environment, instructions and experience
Experimental Design
1. Independent Groups
  1. Two groups selected, one does control condition, other does experimental condition
  2. Performance of two groups compared
2. Repeated Measures
  1. One group selected, do both the control and the experimental condition
  2. Performance in each condition compared
3. Matched Pairs
  1. One group chosen, then another based on characteristics of participants in the first group. Carried out like IGD
  2. Performance of two groups compared

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Experiments- Method, Control of Variables, Design, Types

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	Created by Grace Fawcitt over 6 years ago