Question

Correlation, Regression, Chi-Square and F Distributions and Nonparametric Statistics.

Explain in detail what is meant by correlation.

a.   Give three examples of a positive correlation and three examples of a negative correlation.
b.   Describe at least one lurking variable for each of the correlations provided in part a.
c.   Describe one outlier that could occur with each of your examples from part a.

Answer 1

3 examples of positive correlation -

1.Wealth and Education level

Lurking variable- The wealth also depends upon how many years a person has been working for, apart from education level.

Outlier- Star sportpersons may have a very high wealth despite not having a lot of education on an average.

2.Weight and Height

Lurking variable- Body fat content may also affect the weight apart from height. A shorter person may have more weight than a taller person if the shorter person has more body fat.

Outlier- People with anorexia may have a low weight even if they are tall.

3.Paycheck and Hours worked

Lurking variable- Efficiency in work is a lurking variable.

Outlier- Anesthesiologist may get paid more for only a few hours of work.

3 examples of negative correlation -

1.Life span of a person and average amount of alcohol consumed in a day

Lurking variable- Life span may also depend upon genetics and nutrition.

Outlier- Some alcohols like wine actually increase lifespan if consumed to within limits.

2.Body weight and Average hours of daily physical activity

Lurking variable- Calories consumed in a day would also affect the body weight.

Outlier- Body builders may have a lot of daily physical activity but still weigh more than an average person of their height due to their muscle mass.

3.Number of aircraft crashes and average hours of pilot experience.

Lurking variable- Quality of aircraft also affects the number of crashes.

Outlier- If the pilot is not fit, the creashes would be more likely despite a lot of experience.