Correlations

• What are the key features of correlational studies?

  • Investigate relationship between co-variables
  • Co-variables = 2 or more variables which are both measured (= no IV/DV)
• What are the strengths of correlational studies?

  • Enable researchers to investigate relationships between co-variables when it would be unethical/impossible/impractical to investigate them using experimental methods
  • Can tell us that there is a relationship + the strength/direction of the relationship
• What are the weaknesses of correlational studies?

  • No IV = no causal relationship between variables
• What is the difference between a correlational study and an experimental study?


  • All experiments have an IV + DV -> correlational studies typically only have 2 co-variables which are both measured
  • Causal relationships can be inferred from experiments but not correlational studies
• What are the different types of correlation?

  • Positive
  • Negative
• What will a positive correlation look like on a scattergraph? Give examples of correlational coefficients linked to positive correlations

  As one co-variable increases, the other co-variable also increases

  • Weak positive correlation: +0.3
  • Strong positive correlation: +0.8
• What will a negative correlation look like on a scattergraph? Give examples of correlational coefficients linked to negative correlations


  As one co-variable increases, the other co-variable decreases

  • Weak negative correlation: -0.3
  • Strong negative correlation: -0.8
• What is a correlational coefficient?

  A number found by putting data about each variable through a statistical test of correlation to test their similarity
• What does the + or - of a correlational coefficient tell us about the relationship between co-variables?

  • + indicates a positive relationship
  • - indicates a negative relationship
• What does the number of the correlational coefficient tell us about the relationship between co-variables?

  The number tells us the strength of the relationship

  • The highest correlational coefficient = 1
  • +1 = perfect positive correlation
  • -1 = perfect negative correlation
  • +1 and -1 = equally strong relationships, just a different direction
  • 0 = no correlation
  • Closer to 1 = stronger relationship, closer to 0 = weaker relationship