7.1: Correlational studies

Question 1

Twenty depressed patients were treated using cognitive behavioural therapy.
Over the course of the six-week treatment, each patient’s mood was monitored every week using a self-report mood scale (where a score of 20 = extremely positive mood and a score of 0 = extremely negative mood).
Each week they also completed a quality of sleep questionnaire which was scored from 10 = excellent sleep to 0 = very poor sleep.

At the end of the study, the researchers correlated each patient’s final mood score with his or her final sleep score.
The results are a scattergram to show the relationship between final mood scores and final sleep scores for 20 patients at the end of therapy, showing a positive correlation.

Outline the type of relationship shown in the results above and suggest why it would not be appropriate for the researchers to conclude that better sleep improves mood (2 marks)

Answer 1

They show a positive correlation, as one variable increases, as the other does

Question 2

Twenty depressed patients were treated using cognitive behavioural therapy.
Over the course of the six-week treatment, each patient’s mood was monitored every week using a self-report mood scale (where a score of 20 = extremely positive mood and a score of 0 = extremely negative mood).
Each week they also completed a quality of sleep questionnaire which was scored from 10 = excellent sleep to 0 = very poor sleep.

At the end of the study, the researchers correlated each patient’s final mood score with his or her final sleep score.
The results are a scattergram to show the relationship between final mood scores and final sleep scores for 20 patients at the end of therapy, showing a positive correlation.

Outline the type of relationship shown in the results above and suggest why it would not be appropriate for the researchers to conclude that better sleep improves mood (2 marks).
They show a positive correlation, as one variable increases, as the other does.
However, what?

Answer 2

However, correlation doesn’t show causation

Question 3

Twenty depressed patients were treated using cognitive behavioural therapy.
Over the course of the six-week treatment, each patient’s mood was monitored every week using a self-report mood scale (where a score of 20 = extremely positive mood and a score of 0 = extremely negative mood).
Each week they also completed a quality of sleep questionnaire which was scored from 10 = excellent sleep to 0 = very poor sleep.

At the end of the study, the researchers correlated each patient’s final mood score with his or her final sleep score.
The results are a scattergram to show the relationship between final mood scores and final sleep scores for 20 patients at the end of therapy, showing a positive correlation.

Outline the type of relationship shown in the results above and suggest why it would not be appropriate for the researchers to conclude that better sleep improves mood (2 marks).
They show a positive correlation, as one variable increases, as the other does.
However, correlation doesn’t show causation, only what?

Answer 3

However, correlation doesn’t show causation, only a relationship between the 2 variables

Question 4

What type of graph would be used to display correlational data? (1 mark)

Answer 4

A scattergram would be used to display the correlational data