Chapter 4: Correlation Analysis

Many statistical studies focus on correlation. Are the values of one variable related to the values of another variable? For example, it can be investigated whether defect-free production is related to the working time in the relevant job. Correlation analysis determines whether there is a relationship between the variables, and when such a relationship is detected, it determines its direction and strength.

Correlation techniques are used to study relationships. In order to interpret the correlation coefficients, it is necessary to know how the variables are measured. Random variables are said to be correlated if the values of one variable are linearly related to the values of the other variable. Variables are linearly related if the relationship between variables can be explained by a straight line.