Regression

The Casio makes regression analysis easy. First, one enters the data set. We illustrate with an example of linear regression. Nonlinear regression is done in a similar way. Consult TechSkills 2: Regression for further details.

Linear Regression

Linear regression is the process of fitting a straight line to a data set. A linear function has the form y = ax + b. The task of linear regression is to determine values for a and b that create the straight line that best fits the given data. For example, consider the following data set1.

 Plot 1 2 3 4 5 6 7 8 9 10 11 12 Fertilizer, X (lbs/100ft2) 0 0 5 5 10 10 15 15 20 20 25 25 Yield, Y (bushels) 4 6 10 7 12 10 15 17 18 21 23 22

Our first task is to enter the data set into the Casio. Press the MENU key to display the MAIN MENU. Press 2 to select the STAT menu. A spreadsheet is displayed. Enter the fertilizer amounts in List 1 and the yield data in List 2. Use the thumb pad to navigate from List 1 to List 2.

After the data set is entered and checked for accuracy, we are ready to see a plot of the data. Press F1 to access the GRAPH menu. Press 1 to select 1:S-Grph1, statistical graph 1. A graph of the data set appears.

Notice that it looks reasonable to fit a straight line through the displayed data points. A regression analysis is done as follows.

Press F4 to select CALC. Press 2 to select 2:Linear. The screen now displays the values for the linear form y=ax+b for the straight line of best fit. Here, to three decimal places, the linear equation of best fit is y = .717x + 4.786.

Press F5 to select COPY to copy the linear regression equation into the Graph Func editor.