Correlations

• What is correlation in research?

  A mathematical technique investigating an association between two variables, called co-variables.
• What do correlations illustrate?

  The strength and direction of an association between two or more co-variables.
• How are correlations plotted?

  Correlations are plotted on a scattergram.
• In a scattergram, which variable is on the x-axis?

  One co-variable is on the x-axis, and the other is on the y-axis.
• What are the types of correlations represented in scattergrams?

  • Positive Correlation: As one co-variable increases, so does the other.
  • Negative Correlation: As one co-variable increases, the other decreases.
  • Zero Correlation: No relationship between the two variables.
• What is an example of a positive correlation?


  As anxiety levels increase, the number of caffeine drinks per day also increases.
• What is an example of a negative correlation?


  As the number of caffeine drinks per day increases, hours of sleep per night decreases.
• What does zero correlation indicate?

  There is no relationship between the two variables.
• How do correlations differ from experiments?

  • In an experiment, the independent variable (IV) is manipulated to measure its effect on the dependent variable (DV).
  • In a correlation, there is no manipulation, so cause and effect cannot be established.
• Why can't we assume cause and effect from a strong positive correlation?

  Because other variables, called intervening variables, may influence the relationship.
• What are intervening variables?


  Other variables that can influence the relationship between the two co-variables.
• What are the weaknesses of correlations?

  • Can only tell us how variables are related, not why.
  • Cannot demonstrate cause and effect.
  • Vulnerable to misuse by media.
• What is the third-variable problem?

  It refers to an unaccounted variable that may influence the relationship between two co-variables.
• What are the strengths of using correlations in research?

  • Useful as a starting point for further research.
  • Can show interesting relationships between two things.
  • Relatively quick and economical to carry out.
• What is a correlation coefficient?

  A numerical value between -1 and +1 that shows the strength and direction of the relationship between two variables.
• What does a correlation coefficient of +1 indicate?

  A perfect positive correlation.
• What does a correlation coefficient of -1 indicate?

  A perfect negative correlation.
• What does a correlation coefficient of 0 indicate?

  There is no relationship between the two variables.
• How do correlation coefficients relate to the strength of relationships?

  • The closer the coefficient is to -1 or +1, the stronger the relationship.
  • The closer to 0, the weaker the relationship.
• What statistical tests can be used to calculate correlation coefficients?

  Spearman’s rho and Pearson's r.
• What do statistical tests of correlation look for?

  A relationship between co-variables rather than a difference between two sets of scores.
• How are correlation coefficients represented?

  • Correlation coefficients are represented as r.
  • Values range from -1 to +1.