ABSTRACT
We have seen regression equations in daily life. For instance, the maximum attainable heart rate (MAHR) of a person at a certain age can be estimated by
MAHR = 220 – 1 × Age
The “1 × Age” is usually written simply as “Age.” You may have seen this equation on treadmills in gymnasiums. This is a simple form of linear regression equation. A person who is 40 years old is accordingly estimated to have MAHR = 220 – 40 = 180. The left-hand side of the equation is the dependent variable (MAHR). The right-hand side includes an intercept (220) and the product of a regression coefficient (1) and the independent variable. In some scientific disciplines, it is common to use the phrases outcome variable and exposure variable instead of dependent and independent variables, respectively. Furthermore, in the statistics literature, independent variables are sometimes referred to as covariates. We use these phrases interchangeably.
