Method for mathematically modeling a relationship and is used in prediction and description. Unknown values for the dependent values can be estimated by what is known about the corresponding independent variables. Independent and dependent variables must be at least interval scale. Regression analysis comes in various forms and is very useful to parse out the contributions individual variables make to an outcome. Multivariate and univariate regression are distinguished by the number of independent variables. At least one PDD algorithm uses a form of regression analysis.