reseach methods

• Laboratory experiment


  Experimenter has full control over what happens in the experiment, environmental factors and instructions are highly controlled, only one factor (independent variable) changes between conditions
• Laboratory experiment


  • High internal validity, highly replicable
  • May lack external validity, ecological validity, and mundane realism, prone to demand characteristics
• Field experiment


  Conducted in the real world, natural setting
• Field experiment


  • Increased external validity and ecological validity, reduced demand characteristics
  • Lack of control over extraneous variables, reduced internal validity
• Natural experiment


  Levels of independent variable have already happened naturally, researcher just measures change in dependent variable
• Natural experiment


  • Allow research in areas not possible otherwise, high external validity
  • Lack of control over extraneous variables, reduced internal validity, not replicable
• Quasi-experiment


  Participants cannot be randomly assigned to different levels of the independent variable
• Quasi-experiment


  • Only way to study certain factors, but confounding variables may exist that differ systematically between conditions
• Experimental method


  Manipulation of an independent variable (IV) to have an effect on the dependent variable (DV), which is measured and stated in results
• Aims


  General statement made by the researcher which tells us what they plan on investigating, the purpose of their study
• Hypotheses


  Precise statement which clearly states the relationship between the variables being investigated
• Directional hypothesis


  States the direction of the relationship that will be shown between the variables
• Non-directional hypothesis


  Does not state the direction of the relationship between the variables
• Independent variable (IV)


  Aspect of the experiment which has been manipulated by the researcher or simply changes naturally to have an effect on the DV
• Dependent variable (DV)


  Aspect of the study which is measured by the researcher and has been caused by a change to the IV
• Experimental condition


  Condition where the IV is manipulated
• Control condition


  Condition where the IV is not manipulated
• Operationalisation


  Researcher clearly defining the variables in terms of how they are being measured
• Extraneous variable


  Variable other than the IV that affects the DV but does not vary systematically with the IV
• Confounding variable


  Variable other than the IV that affects the DV and does change systematically with the IV
• Demand characteristics


  Cues the researcher or research situation gives that make the participant guess the aim of the investigation
• Participant reactivity


  Participants acting differently within the research situation from how they would usually act
• Investigator effects


  Unwanted influence from the researcher's behaviour, either conscious or unconscious, on the DV measured
• Randomisation


  Use of chance to reduce the effects of bias from investigator effects
• Standardisation


  Using the exact same formalised procedures and instructions for every single participant
• Types of experiments


  • Laboratory
  • Field
  • Quasi
  • Natural
• Population


  Group of people from whom the sample is drawn
• Sampling methods


  • Opportunity sampling
  • Random sampling
  • Systematic sampling
  • Stratified sampling
  • Volunteer sampling
• Experimental designs


  • Independent groups design
  • Repeated measures
  • Matched pairs
• Pilot study


  Small-scale version of an investigation done before the real investigation to identify potential problems
• Single-blind procedure


  Researchers do not tell participants if they are being given a test treatment or control treatment
• Double-blind procedure


  Neither the participants nor the researchers know which participants are receiving the test treatment or control treatment
• Less of a problem than matching participants in experiments
• Matching participants


  • Time consuming and expensive
  • A large pool of potential participants is needed which can be hard to get
  • Difficult to know which variables are appropriate for the participants to be matched
• Pilot study


  A small-scale version of an investigation which is done before the real investigation is undertaken
• Purpose of pilot studies

  • Allow potential problems of the study to be identified and the procedure to be modified to deal with these
  • Saves money and time in the long run
• Single-blind procedure


  A research method in which the researchers do not tell the participants if they are being given a test treatment or a control treatment
• Double-blind procedure


  A research procedure in which neither the participants nor the experimenter knows who is receiving a particular treatment
• Purpose of double-blind procedures

  • Prevent bias in research results
  • Prevent bias due to demand characteristics or the placebo effect
  • Reduce investigator effects as the investigator is unable to unconsciously give participants clues as to which condition they are in
• Control group/condition


  Sets a baseline whereby results from the experimental condition can be compared to results from this one