Correlations

Question 1

What is a correlation?

Answer 1

A non-experimental method used to measure how strong the relationship is between two (or more) variables
Correlation illustrates the strength and direction of an association and is plotted on a scattergram

Question 2

What is the difference between correlations and experiments?

Answer 2

In an experiment, the researcher controls or manipulates the independent variable to measure the effect on the dependent variable
In a correlation, there is no manipulation of one variable, and therefore we cannot establish cause and effect between one co-variable and another

Question 3

Give example of correlation coefficients for perfect positive, no correlation, perfect negative, strong correlation and weak correlation

Answer 3

Perfect positive = +1
No correlation = 0
Perfect negative = -1
Strong correlation = +0.8 or -0.8
Weak correlation = +0.3 or -0.3

Question 4

Name some strengths of correlations

Answer 4

1. Knowing the strength and direction of a relationship provides a precise and quantifiable measure of how two variables are related
2. May suggests future research ideas
3. Relatively quick and economical to carry out
4. No need for a controlled environment and no manipulation of variable is required
5. Less time consuming than experiments because you can use secondary data

Question 5

Name some limitations of correlations

Answer 5

1. Can’t show cause and effect between variables so we don’t know which co-variable is causing the other to change (there could even be an untested intervening third variables that is causing the relationship)
2. Correlations can occasionally be misused or misinterpreted
3. Relationships between variables are sometimes presented as casual when they aren’t - especially by the media EG: “people from broken homes are more likely to become criminals”, even though the actual changing variable may be poverty

Question 6

How is a correlational hypothesis different to a hypothesis for an experiment?

Answer 6

Not the same because there is no IV or DV in a correlation - but the hypothesis still has to clearly state the expected relationship between variables

Question 7

Give an example of a directional hypothesis for a correlation

Answer 7

“There is a positive correlation between the price of a chocolate bar and its tastiness rating out of 20”

Question 8

Give an example of a non-directional hypothesis for a correlation

Answer 8

“There is a correlation between the price of a chocolate bar and it’s tastiness rating out of 20”