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Business Calculus with Excel

Section A.3 From Section 1.5 Adding and Using Best Fit Curves (Trendlines)

  • Add a trendline to a chart To add a trendline, we build a chart with the data, select the data and add a scatterplot, then right-click on a ploint and select "Add Trendline" from the drop down menu 1.5.2. By defualt, Excel will add the best fitting line. (pic AddTrendlineMenu )
  • Find the equation of the trendline. We use the options pallette to format the trendline. Scroll down and select the option to Display Equation on Chart 1.5.3. If you do not make this selection when creating the trendline, you can right-click (Control-click on a mac) to bring the menu up again.
  • Although Excel uses the term Trenline, twe can Find a best fit curve for some non-linear models. Select the approriate option from the Trendline Oprions Menu 1.5.3. Options will be grayed out if the trendline model will not fit the given data. (E.g., we cannot make an exponential fit for data that includes negative values.)
  • When we try toadd the predicted function back to the chart we need to translate from mathematical notation to Excel notation. (E.g., we need to use * to make multiplication explicit and ^ to make exponantiation explicit.)
  • Sometimes we want to change the precision of the coefficients in the trendline, particularly when using the equation to make prediction far from the basepoint. You right-click (Control-click on a mac) on the label to "Format Trendline Label" 1.5.8. Choose Number, then category Number or Scientific, and choose the number of digits.