Correlations

• Association

  Illustrates the strength and direction of an association between two co-variables.
• Scattergram

  Correlations are plotted on a scattergram. One co-variable is on the x-axis, the other on the y.
• Types of correlation

  Positive - co variables rise or fall together

  Negative - one variable rises and the other falls

  Zero - no relationship between the variables
• Differences between correlations and experiments

  • In an experiment the researcher manipulates the IV and records the effect on the DV. In a correlation there is no manipulation of variables and so cause and effect cannot be demonstrated.
  • In a correlation the influence of EVs is not controlled, so it may be that a third 'untested' variable is causing the relationship
• Pros and cons of correlations

  Pros:

  • useful starting point for research
  • relatively economical (less money and time)

  Cons:

  • no cause and effect established
  • method used to measure the variables may be flawed