Correlation and Comparison of Variables

Abstract

Correlation concerns techniques that are mostly used to assess the association or degree of dependence between the dependent response variable (y) and the independent or control variable (x). This uses the concept of the regression line from the previous chapter, but it is rarely a mathematical model of underlying theoretical relationship or causal association. The value of the correlation coefficient and its significance qualify the strength of the association. This may be illustrated by confidence limits on the slope and intercept of the regression line, and confidence regions about the regression line that will be discussed below.