Types of Correlations.
There are three types of correlations :
Postive Correlation- As one variable increases, so does the other. (the closer to +1, the stronger the positive correlation)
Eg. The bigger the height of a person, the larger their shoe size.
Negative Correlation - As one variables increases, the other decreases. (the closer to -1, the stronger the negative correlation)
Eg. The more alcohol consumed, the worse the driving performance.
No(zero) Correlation - No relationship between the two variables.
Advantages and Disadvantages of Correlational Anal
+ Can be used where experimental manipulation would be unethical or impossible.
+ Can suggest further avenues of research.
+ When only one variable is known, the other can be predicted.
- It only examines the strength of the relationship between the two variables not a cause and effect between variables.
- The relationship may be effected by extraneous variables.
- Correlation coefficients overlook relationships that are not linear.
Strength of Correlations
The closer a correlation coefficient is to 1,the stronger the correlation is. The sign doesnt matter, +1 is as strong as -1.
Correlation Coefficient Value Strength of the Relationship
1.0 Perfect positive
0.8 Strong positive
0.5 Moderate positive
0.3 Weak positive
0.1 Very weak positive
0 No relationship
-0.1 Very weak negative
-0.3 etc Weak negative