Correlations

• correlation


  a method used to analyse the association between two co-variables
• co-varaible


  the variables measured in a correlation
• how correlations are plotted


  using a scattergram
• positive correlation


  as one co-varaible increases or decreases, the other does too
• negative correlation


  as one co-variable increases or decreases, the other does the opposite
• zero correlation


  there is no relationship between the co-variables
• intervening variables


  other variables which may have an effect on the co-variables
• strengths of correlations


  -more ethical way of investigating some topics as does not involve manipulation of variables

  -useful preliminary tool to justify further investigation using an experiment- if there is a string association between two co-variables then is a useful starting point to explore possible experimental study to establish cause and effect relationship
• weaknesses of correlations


  -cannot demonstrate cause and effect between variables- we do not know which variable is causing which

  -can lead to misinterpretations- relationships between variables are often presented as casual 'facts' when they may not be (particularly in the media)

  -intervening variables- the 2 co-variables could be linked due to unknown, intervening variables
• correlation coefficient


  a number between -1 and +1 that tells us the strength and direction of the relationship between the two co-variables
• what the sign before the correlation coefficient tells us


  the direction of the relationship between two co-variables (positive or negative)