Linear Regression Analysis 73Based on linear trends using regression analysis, we can now estimatethat the activity will cost $7,611 for period 10 and $8,644.50 for period 15.In the discussion on linear regression analysis and the example above,the independent variable was t (the time period). However, the linearregression technique can also be used to determine association or cau-sation between two variables; that is, the direct relationship or impactof one factor on another (for example, the manner in which smokingincreases one's risk of heart disease). In such cases, we use the notation xfor the independent variable and y for the dependent variable. The linearregression equation in such cases would b