correlations

• correlation

  a measure of how strongly two or more variables are related to each other e.g. height is positively correlated to shoe size as the taller someone is, the larger their shoe size tends to be

  no manipulation of data, conditions or groups

  no IV or DV, just co-variables
• positive correlation

  as one variable increases, so does the other
• negative correlation

  as one variable increases, the other decreases
• no correlation

  there is no relationship between the variables
• correlation coefficient

  a number between -1 and 1 that tell us how strong the relationship is
• hypotheses for correlation

  can't show cause and effect

  talk about the relationship between the two variables

  use the term significant

  must clearly state the variables and how they have been operationalised

  don't use the words cause, effect or difference
• null hypothesis: there will be no relationship


  there will be no significant relationship between variable 1 and variable 2
• alternate hypothesis

  one tailed - there will be a significant positive/negative relationship between variable 1 and variable 2

  two tailed - there will be a significant relationship between variable 1 and variable 2
• strengths of correlations

  • makes a good pilot study to generate a hypothesis for an experiment
  • can research variables that would be unethical to manipulate
  • can understand the relationship between two variables - positive/negative, weak/strong
• weaknesses of correlations

  • correlations do not show causation
  • they have the same weaknesses as whatever method was used to gather the data (observation/self report)
  • tell us nothing about other variables that may be the real cause
  • correlations are often misleading