Measures of Association
Measures of association encompass methods designed to identify relationships between two or more variables and statistics used to measure the relationship when it exists. Although the terms correlation and association are often used interchangeably, correlation in a stricter sense refers to linear correlation and association refers to any relationship between variables, including the relationship between two categorical variables.
Choosing the Correct Method
Choosing the correct method to measure association involves a determination of the data characteristics for each variable. Data may be measured on an interval/ratio scale, an ordinal/rank scale, or a nominal/categorical scale. These three characteristics can be thought of as continuous, integer, and qualitative categories.
Pearson's Correlation Coefficient
A typical example for measuring the association between two variables measured on an interval/ratio scale is the analysis ...