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Microsoft Excel 2007 and Tools
for Statistical Analysis
David R. Anderson, Dennis J. Sweeney,
and Thomas A. Williams
Microsoft Excel 2007, part of the Microsoft Office 2007 system, is a spreadsheet program that can be used to organize and analyze data, perform complex calculations, and create a wide variety of graphical displays. We assume readers of this primer are familiar with basic Excel operations such as selecting cells, entering formulas, copying, and so on. But, we do not assume readers are familiar with Excel 2007 or the use of Excel for statistical analysis. The purpose of this primer is twofold. First, we provide an overview of Excel 2007 and discuss the basic operations needed to work with Excel 2007 workbooks and worksheets. Second, we provide an overview of the tools that are available for conducting statistical analysis with Excel. These include Excel functions and formulas which allow users to con- duct their own analyses and add-ins that provide more comprehensive analysis tools. Excel’s Data Analysis add-in, included with the basic Excel system, is a valuable tool for conducting statistical analysis. In the last section of this primer we provide instructions for installing the Data Analysis add-in. Other add-ins have been developed by outside sup- pliers to supplement the basic statistical capabilities provided by Excel. In the last section we also discuss two commercially available add-ins developed by Palisade Corporation: StatTools and PrecisionTree.
OVERVIEW OF MICROSOFT EXCEL 2007
When using Excel for statistical analysis, data is displayed in workbooks, each of which contains a series of worksheets that typically include the original data as well as any re- sulting analyses, including charts. Figure 1 shows the layout of a blank workbook created each time Excel is opened. The workbook is named Book1, and consists of three worksheets named Sheet1, Sheet2, and Sheet3. Excel highlights the worksheet currently displayed (Sheet1) by setting the name on the worksheet tab in bold. To select a different worksheet simply click on the corresponding tab. Note that cell A1 is initially selected. The wide bar located across the top of the workbook is referred to as the Ribbon. Tabs, located at the top of the Ribbon, provide quick access to groups of related commands. There are eight tabs: Home; Insert; Page Layout; Formulas; Data; Review; View, and Add-Ins. Each tab contains a series of groups of related commands. Note that the Home tab is se- lected when Excel is opened. Figure 2 displays a portion of the Home tab. Under the Home tab there are seven groups of related commands: Clipboard; Font; Alignment; Number; Styles; Cells; and Editing. Commands are arranged within each group. For example, to change selected text to boldface, click the Home tab and click the Bold button in the Font group. Figure 3 illustrates the location of the Office Button, the Quick Access Toolbar, and the Formula Bar. When you click the Office Button, Excel provides a list of workbook options such as opening, saving, and printing (worksheets). The Quick Access Toolbar allows you to quickly access these workbook options. For instance, the Quick Access Toolbar shown in Figure 3 includes an Open button that can be used to open files without having to first click the Office Button. To add or remove features on the Quick Access Toolbar click the Customize Quick Access Toolbar button on the Quick Access Toolbar.
A workbook is a file containing one or more worksheets.
The Formula Bar contains a Name box, the Insert Function button , and a Formula box. In Figure 3, “A1” appears in the Name box because cell A1 is selected. You can select any other cell in the worksheet by using the mouse to move the cursor to another cell and clicking or by typing the new cell location in the name box. The Formula box is used to dis- play the formula in the currently selected cell. For instance, if you had entered A1A into cell A3, whenever you select cell A3 the formula A1A2 will be shown in the Formula box. This feature makes it very easy to see and edit a formula in a particular cell. The Insert Function button allows you to quickly access all of the functions available in Excel. Later we show how to find and use a particular function.
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Tabs Contain Names of Worksheets
Name of Workbook (^) Ribbon
Cell A1 is selected
FIGURE 1 BLANK WORKBOOK CREATED WHEN EXCEL IS OPENED
Basic Workbook Operations Figure 4 illustrates the worksheet options that can be performed after right clicking on a worksheet tab. For instance, to change the name of the current worksheet from “Sheet1” to “Data,” right click the worksheet tab named “Sheet1” and select the Rename option. The current worksheet name (Sheet1) will be highlighted. Then, simply type the new name (Data) and press the Enter key to rename the worksheet. Suppose that you wanted to create a copy of “Sheet1.” After right clicking the tab named “Sheet1,” select the Move or Copy option. When the Move or Copy dialog box ap- pears, select Create a Copy and click OK. The name of the copied worksheet will appear as “Sheet1 (2).” You can then rename it, if desired. To add a worksheet to the workbook, right click any worksheet tab and select the Insert option; when the Insert dialog box appears, select Worksheet and click OK. An additional blank worksheet titled “Sheet 4” will appear in the workbook. You can also insert a new worksheet by clicking the Insert Worksheet tab button that appears to the right of the last worksheet tab displayed. Worksheets can be deleted by right clicking the worksheet tab and choosing Delete. After clicking Delete, a window will appear warning you that any data appearing in the worksheet will be lost. Click Delete to confirm that you do want to delete the worksheet. Worksheets can also be moved to other workbooks or a different position in the current workbook by using the Move or Copy option.
Creating, Saving, and Opening Files Data can be entered into an Excel worksheet by manually entering the data into the work- sheet or by opening another workbook that already contains the data. As an illustration of manually entering, saving, and opening a file we will use an example from Chapter 2 of the Anderson, Sweeney, and Williams statistics texts involving data for a sample of 50 soft drink purchases. The original data are shown in Table 1. Suppose you have just opened Excel and want to work with this data. A blank workbook containing three worksheets will be displayed. The soft drink data can now be entered man- ually by simply typing it into one of the worksheets. If Excel is currently running and no blank workbook is displayed, you can create a blank workbook using the following steps: Step 1: Click the Office button Step 2: Click New in the list of options
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FIGURE 4 WORKSHEET OPTIONS OBTAINED AFTER RIGHT CLICKING
ON A WORKSHEET TAB
Step 3: When the New Workbook dialog box appears: Select Blank and recent under Templates Double click Blank Workbook
A new workbook containing three worksheets labeled Sheet1, Sheet2, and Sheet3 will appear. Suppose we want to enter the data for the sample of 50 soft drink purchases into Sheet of the new workbook. First, we enter the label “Brand Purchased” into cell A1; then, we enter the data for the 50 soft drink purchases into cells A2:A51. As a reminder that this worksheet contains the data, we will change the name of the worksheet from “Sheet1” to “Data” using the procedure described previously. Figure 5 shows the data worksheet we have just developed. Before doing any analysis with these data, we recommend that you first save the file; this will save you from having to reenter the data in case something happens that causes Excel to close. To save the workbook using the filename SoftDrink we perform the following steps: Step 1: Click the Office button Step 2: Click Save As in the list of options Step 3: When the Save As dialog box appears: In the Save in box select the location where you want to save the file Type the filename SoftDrink in the File name box Click Save
Excel’s Save command is designed to save the file as an Excel 2007 workbook. As you work with the file to do statistical analysis you should follow the practice of periodically saving the file so you will not lose any statistical analysis you may have performed. Simply fol- low the procedure described above using the Save command. Sometimes you may want to create a copy of an existing file. For instance, suppose you would like to save the soft drink data and any resulting statistical analysis in a new file
Microsoft Excel 2007 and Tools for Statistical Analysis 5
Coke Classic Sprite Pepsi Diet Coke Coke Classic Coke Classic Pepsi Diet Coke Coke Classic Diet Coke Coke Classic Coke Classic Coke Classic Diet Coke Pepsi Coke Classic Coke Classic Dr. Pepper Dr. Pepper Sprite Coke Classic Diet Coke Pepsi Diet Coke Pepsi Coke Classic Pepsi Pepsi Coke Classic Pepsi Coke Classic Coke Classic Pepsi Dr. Pepper Pepsi Pepsi Sprite Coke Classic Coke Classic Coke Classic Sprite Dr. Pepper Diet Coke Dr. Pepper Pepsi Coke Classic Pepsi Sprite Coke Classic Diet Coke
TABLE 1 DATA FROM A SAMPLE OF 50 SOFT DRINK PURCHASES
Keyboard shortcut: To save the file, press CTRL S
Step 3: When the Open dialog box appears: In the Look in box select the location where you previously saved the file Enter the filename SoftDrink in the File name box Click Open
The procedures we showed for saving or opening a workbook begin by clicking on the Office Button to access the Save and Open commands. Once you have used Excel for awhile you will probably find it more convenient to add these commands to the Quick Access Toolbar.
USING EXCEL FUNCTIONS
Excel 2007 provides a wealth of functions for data management and statistical analysis. If we know what function is needed, and how to use it, we can simply enter the function into the appropriate worksheet cell. However, if we are not sure what functions are available to accomplish a task or are not sure how to use a particular function, Excel can provide assistance.
Finding the Right Excel Function To identify the functions available in Excel, click the Formulas tab on the Ribbon and then click the Insert Function button in the Function Library group. Alternatively click the button on the formula bar. Either approach provides the Insert Function dialog box shown in Figure 6.
Microsoft Excel 2007 and Tools for Statistical Analysis 7
FIGURE 6 INSERT FUNCTION DIALOG BOX
The Search for a function box at the top of the Insert Function dialog box enables us to type a brief description of what we want to do. After doing so and clicking Go, Excel will search for and display, in the Select a function box, the functions that may accomplish our task. In many situations, however, we may want to browse through an entire category of functions to see what is available. For this task, the Or select a category box is helpful. It contains a drop-down list of several categories of functions provided by Excel. Figure 6 shows that we selected the Statistical category. As a result, Excel’s statistical functions ap- pear in alphabetic order in the Select a function box. We see the AVEDEV function listed first, followed by the AVERAGE function, and so on. The AVEDEV function is highlighted in Figure 6, indicating it is the function currently selected. The proper syntax for the function and a brief description of the function appear below the Select a function box. We can scroll through the list in the Select a function box to display the syntax and a brief description for each of the statistical functions that are available. For instance, scrolling down farther, we select the COUNTIF function as shown in Figure 7. Note that COUNTIF is now highlighted, and that immediately below the Se- lect a function box we see COUNTIF(range,criteria), which indicates that the COUNTIF function contains two arguments, range and criteria. In addition, we see that the description of the COUNTIF function is “Counts the number of cells within a range that meet the given condition.” If the function selected (highlighted) is the one we want to use, we click OK; the Function Arguments dialog box then appears. The Function Arguments dialog box for the COUNTIF function is shown in Figure 8. This dialog box assists in creating the appropriate
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FIGURE 7 DESCRIPTION OF THE COUNTIF FUNCTION IN THE INSERT FUNCTION
DIALOG BOX
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FIGURE 10 COMPLETED FUNCTION ARGUMENTS DIALOG BOX FOR THE COUNTIF FUNCTION
the COUNTIF function was inserted into cells D2:D6. The value worksheet shows the proper class frequencies as computed. We illustrated the use of Excel’s capability to provide assistance in using the COUNTIF function. The procedure is similar for all Excel functions. This capability is especially help- ful if you do not know what function to use or forget the proper name and/or syntax for a function.
FIGURE 9 EXCEL WORKSHEET WITH SOFT DRINK DATA AND LABELS FOR
THE FREQUENCY DISTRIBUTION WE WOULD LIKE TO CONSTRUCT
A B C D E F 1 Brand Purchased Soft Drink Frequency 2 Coke Classic Coke Classic 3 Diet Coke Diet Coke 4 Pepsi Dr. Pepper 5 Diet Coke Pepsi-Cola 6 Coke Classic Sprite 7 Coke Classic 8 Dr. Pepper 9 Diet Coke 10 Pepsi 45 Pepsi 46 Pepsi 47 Pepsi 48 Coke Classic 49 Dr. Pepper 50 Pepsi 51 Sprite 52
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FIGURE 11 EXCEL WORKSHEET SHOWING THE USE OF EXCEL’S COUNTIF FUNCTION
TO CONSTRUCT A FREQUENCY DISTRIBUTION
A B C D E 1 Brand Purchased Soft Drink Frequency 2 Coke Classic Coke Classic COUNTIF($A$2:$A$51,C2) 3 Diet Coke Diet Coke COUNTIF($A$2:$A$51,C3) 4 Pepsi Dr. Pepper COUNTIF($A$2:$A$51,C4) 5 Diet Coke Pepsi-Cola COUNTIF($A$2:$A$51,C5) 6 Coke Classic Sprite COUNTIF($A$2:$A$51,C6) 7 Coke Classic 8 Dr. Pepper 9 Diet Coke 10 Pepsi 45 Pepsi 46 Pepsi 47 Pepsi 48 Coke Classic 49 Dr. Pepper 50 Pepsi 51 Sprite 52
USING EXCEL ADD-INS
Excel’s Data Analysis Add-In Excel’s Data Analysis add-in, included with the basic Excel package, is a valuable tool for conducting statistical analysis. Before you can use the Data Analysis add-in it must be in- stalled. To see if the Data Analysis add-in has already been installed, click the Data tab on the Ribbon. In the Analysis Group you should see the Data Analysis command. If you do not have an Analysis Group and/or the Data Analysis Command does not appear in the Analysis Group, you will need to install the Data Analysis Add-In. The steps needed to in- stall the Data Analysis Add-In are as follows: Step 1: Click the Office Button Step 2: Click Excel Options (on the taskbar at the bottom) Step 3: When the Excel Options dialog box appears: Select Add-Ins from the list of options (on the pane on the left) In the Manage box, select Excel Add-Ins (in the next to last row) Click Go
A B C D E 1 Brand Purchased Soft Drink Frequency 2 Coke Classic Coke Classic 19 3 Diet Coke Diet Coke 8 4 Pepsi Dr. Pepper 5 5 Diet Coke Pepsi-Cola 13 6 Coke Classic Sprite 5 7 Coke Classic 8 Dr. Pepper 9 Diet Coke 10 Pepsi 45 Pepsi 46 Pepsi 47 Pepsi 48 Coke Classic 49 Dr. Pepper 50 Pepsi 51 Sprite 52
