Correlations

• Correlation


  A measure of the extent to which two factors vary together, and thus of how well either factor predicts the other.
• Co-variables


  The variables investigated within a correlation e.g. height and weight.
• Positive correlation


  - A correlation where, as one variable increases, the other also increases, or as one decreases so does the other.

  - Both variables move in the same direction.

  
• Negative correlation


  A finding that two factors vary systematically in opposite directions, one increasing as the other decreases.

  
• Zero correlation


  When there is no relationship between the co-variables.

  
• Strengths of correlations


  - Can be used when it is impractical/unethical to manipulate variables

  - Can rule out a causal relationship if there is zero correlation
• Limitations of correlations


  - Correlation does not equal causation

  - Correlations can sometimes be explained by third (extraneous) variables