Correlations:

• What is a correlation?

  a correlation is a relationship between two variables (co-variables)
• How can a correlation be illustrated/shown?

  using a scatter-gram
• What are co-variables?

  The variables investigated within a correlation, for example height and weight. They are not referred to as the independent and dependent variables because a correlation investigates the association between the variables, rather than trying to show a cause-and-effect relationship
• What is a positive correlation?

  The co-variables will increase together for a positive correlation
• What is a negative correlation?

  As one co-variable increases, the other co-variable decreases
• Correlation coefficient:

  • The correlation coefficient is a number
  • It represents the strength of the relationship between the co-variables
  • It has a maximum value of +1 and a minimum value of -1
  • +1 represents a perfect positive correlation
  • -1 represents a perfect negative correlation
  • 0 represents zero correlation
  • Therefore, the strength of the correlation increases as the correlation coefficient moves away from 0 towards either +1 or -1
• What is manipulated in an experiment?

  Independent variable (IV)
• Why are extraneous variables controlled in experiments?

  To establish a causal relationship
• What can be established when an IV is manipulated?

  A causal relationship (cause and effect)
• What does high internal validity indicate?

  Manipulation of IV caused effect in DV
• What is not manipulated in a correlation?

  Independent variable (IV)
• What happens to co-variables in a correlation?

  They are simply measured
• What cannot be established in a correlation?

  A causal relationship (cause and effect)
• Why can't we be sure that a change in one co-variable caused a change in another?

  Because there is no manipulation of IV
• What does low internal validity indicate in a correlation?

  We cannot establish a causal relationship
• What is the main difference between correlations and experiments?

  Experiments manipulate IV, correlations do not
• What are strengths of correlations:

  • Correlations can be used when it would be unethical or impractical to manipulate variables as they can make use of existing data
  • Correlations have value to exploratory research as, if a correlation is significant, further research is justified
• What are limitations of correlations:

  • There is no manipulation of an IV so a causal relationship (cause and effect) cannot be established. We cannot be sure that a change in one co-variable caused a change in the other co-variable. This means internal validity is low.
  • There may be another, unknown variable that can explain why the co-variables are linked. These other variables are known as intervening variables and effect both of the co-variables.