4.1 Regression analysis is a statistical procedure that studies the relations between two or more numerical variables and utilizes existing data to determine a model equation for prediction of one variable from another. In this standard, a simple linear regression model, that is, a straight line relationship between two variables, is considered (1, 2).3

1.1 This practice covers regression analysis methodology for estimating, evaluating, and using the simple linear regression model to define the relationship between two numerical variables.

1.2 The system of units for this practice is not specified. Dimensional quantities in the practice are presented only as illustrations of calculation methods. The examples are not binding on products or test methods treated.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.