4.6 Using Computer Software for Regression

Software such as Excel 2016, Excel QM, and QM for Windows is usually used for the regression calculations. All of these will be illustrated using the Triple A Construction example.

Excel 2016

To use Excel 2016 for regression, enter the data in columns. Click the Data tab to access the data ribbon. Then select Data Analysis, as shown in Program 4.1A. If Data Analysis does not appear on the Data ribbon, the Excel add-in for this has not yet been activated. See Appendix F at the end of the book for instructions on how to activate this. Once this add-in is activated, it will remain on the Data ribbon for future use.

When the Data Analysis window opens, scroll down to and highlight Regression and click OK, as illustrated in Program 4.1A. The Regression window will open, as shown in Program 4.1B, and you can input the X and Y ranges. Check the Labels box because the cells in the first row of the X and Y ranges include the variable names. To have the output presented on this page rather than on a new worksheet, select Output Range and give a cell address for the start of the output. Click the OK button, and the output appears in the output range specified. Program 4.1C shows the intercept (2), slope (1.25), and other information that was previously calculated for the Triple A Construction example.

The sums of squares are shown in the column headed by SS. Another name for error is residual. In Excel, the sum of squares error is shown as the sum of squares residual. The values in this output are the same values shown in Table 4.3:

Sum of squares regression = SSR = 15.625Sum of squares error (residual) = 6.8750Sum of squares total = SST = 22.5

The coefficient of determination (r2) is shown to be 0.6944. The coefficient of correlation (r) is called Multiple R in the Excel output, and this is 0.8333.

Screenshot of Excel screen showing Triple A Construction’s sales and payroll data. A series of tip boxes instruct you to: Go to the Data tab, Select Data Analysis, when the Data Analysis window opens, scroll down to highlight Regression, and click OK.

Program 4.1A Accessing the Regression Option in Excel 2016

Screenshot of the Regression data window that pops up in Excel.

Program 4.1B Data Input for Regression in Excel 2016

Screenshot showing the output from Excel’s regression calculations. Tip boxes highlight pertinent information from the output sheet.

Program 4.1C Excel 2016 Output for Triple A Construction Example

Excel QM

To use Excel QM for regression, from the Excel QM ribbon select the module by clicking Alphabetical - Forecasting - Multiple Regression, as shown in Program 4.2A. A window will open to allow you to specify the size of the problem, as shown in Program 4.2B. Enter a name or title for the problem, the number of past observations, and the number of independent (X) variables. For the Triple A Construction example, there are 6 past periods of data and 1 independent variable. When you click OK, a spreadsheet will appear for you to enter the X and Y data in the shaded area. The calculations are automatically performed, so there is nothing to do after entering the data. The results are seen in Program 4.2C.

Screenshot showing how to run a regression in Excel QM. Tip boxes guide you to Go to the Excel QM tab in Excel 2016, left click on the Alphabetical menu, point the cursor at Forecasting, when options appear, click Multiple Regression.

Program 4.2A Using Excel QM for Regression

Screenshot of Spreadsheet Initialization. Tip boxes instruct you to: Input a title, input the number of past observations, input the number of independent open parens X closed parens variables, and click OK.

Program 4.2B Initializing the Spreadsheet in Excel QM

Screenshot that walks through inputs and automatically calculated results.

Program 4.2C Input and Results for Regression in Excel QM

QM for Windows

To develop a regression equation using QM for Windows for the Triple A Construction Company data, select the Forecasting module and select New. Then choose Least Squares—Simple and Multiple Regression, as illustrated in Program 4.3A. This opens the window shown in Program 4.3B. Enter the number of observations (6 in this example) and specify the number of independent variables (1 in this example). Left-click OK and a window opens allowing you to input the data, as shown in Program 4.3C. After entering the data, click Solve, and the forecasting results shown in Program 4.3D are displayed. The equation as well as other information is provided on this screen. Note the regression equation is displayed across two lines. Additional output, including the ANOVA table, is available by clicking the Window option on the toolbar.

Screenshot showing a drop down menu containing the following items: 1 Time Series Analysis, 2 Least Squares – Simple and Multiple Regression, 3 Regression Projector, and 4 Error Analysis.

Program 4.3A QM for Windows Regression Option in Forecasting Module

Screenshot showing how to create a data set for regression. Tip boxes state to specify the number of observations, in this case 6, to specify the number of variables, in this case 1, and to click OK.

Program 4.3B QM for Windows Screen to Initialize the Problem

Screenshot showing a three column table that includes data for 6 different observations.

Program 4.3C Data Input for Triple A Construction Example

A table of forecasting results is shown. A tip box states that additional information is available by clicking the Window menu. A second tip box instructs that the regression equation is across two lines of the data table.

Program 4.3D QM for Windows Output for Triple A Construction Example

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