TABLE 16-8 The president of a chain of department stores believes that her stores total sales have been showing a linear trend since 1980. She uses Microsoft Excel to obtain the partial output below. The dependent variable is sales (in millions of dollars), while the independent variable is coded years, where 1980 is coded as 0, 1981 is coded as 1, etc. Summary Output Regression Statistics Multiple R R Square Adjusted R Square 0.316 Standard Error Observations 0.604 0.365 4.800 17