Excel Basics 1. Running Excel When you first run Microsoft Excel you see the following menus and toolbars across the top of your new worksheet The Main Menu Bar is located immediately below the Program Title Bar. Commands are grouped into categories such as File, Edit, View, etc. Each menu can be accessed (expanded) by either clicking on the entry with the mouse or holding down the alt key and pressing the underlined letter in the menu entry. Immediately below the Main Menu Bar is the Standard Toolbar. This is a ribbon of icons that are designed to ease your access to commands (usually accessible through the menus). To determine what a particular toolbar icon represents, simply locate the mouse over an icon and its name will be displayed. The Formatting Toolbar (next toolbar shown above) contains shortcuts to commands that change the appearance of text in the worksheet. There are a number of other toolbars that can be displayed by clicking with the right mouse button on the blank area to the right of the displayed toolbars and then selecting the desired toolbars to be displayed. In the above figure, immediately below the Formatting Toolbar is the Formula Bar. The first window in the Formula Bar shows the address of the active cell. Initially it is A1 (meaning that the current cell is in column A and row 1. The Worksheet Area consists of 4,194,304 cells with columns labeled as letters and rows as numbers (i.e., 256 columns and 16,384 rows). Press CTRL+Down Arrow (at the same time) to move to the last row and CTRL+Right Arrow to move to the last column. Scroll Bars are found at the right and at the bottom of the worksheet. Worksheet Tabs are at the lower left of the screen and are initially labeled as Sheet1, Sheet2, etc. The default setting provides 16 of these tabs that you can move through by clicking the arrow to the left of the sheet name. To change the name of a sheet simply double-click on the Sheet name at which time you will be able to edit the name. To rearrange the sheets simply click on a sheet name and while holding down the left mouse button, drag the sheet to the left or right to change the order of the sheets. Some of the statistical functions that we will be discussing today are not necessarily loaded into Excel by default. To ensure that the analysis addins are present (they are 1
not in the default lab settings), do the following: from the Tools menu entry select Add Ins as illustrated below: The following dialog box should then appear: Don t worry about what other add-ins are selected, but click the box next to the Analysis ToolPak (first entry) and then click OK. 2. Formulae In Excel begin with = (usually @ in Quattro) Relative and Specific Values B2 VERSUS B$2 VERSUS $B2 VERSUS $B$2 2
3. Some Commonly Used Keyboard Commands Key Enter Tab Control+Shift+Enter Esc Backspace Delete Arrow keys Home End Control+Home Control+End Control+x Control+v Control+c Control+y Control+f Control+s F1 F4 F9 Tools Options Calculation Action Complete a cell entry and move down in the selection Complete a cell entry and move to the right in the selection Enter a formula as an array formula Cancel a cell entry Delete the character to the left of the insertion point, or delete the selection Delete the character to the right of the insertion point, or delete the selection Move one character up, down, left, or right Move to the beginning of the line Move to the end of the line Move to the beginning of a worksheet Move to the last cell on the worksheet Cut the selection Paste the selection Copy the selection Repeat the last action Opens the Find dialog box Saves your work Opens Help (or at least summons the paperclip!) Makes cell reference absolute or relative in the formula bar (cycles through) Calculate (or recalculate) all sheets in all open workbooks Set manual versus automatic calculation for workbook 4. Selection (Highlighting) Cells If cells are in a contiguous block: o Move the cursor to one corner of the block of cells o Click and hold the mouse button as you drag the cursor to the opposite corner of the block o Release the mouse button when the cursor is in the cell at the opposite corner of the block Or: o Select a cell at one corner of the block of cells o Move the cursor to the opposite of the block using the mouse only o Hold down the Shift key and lick the mouse button Or: o Extend the selection by holding down the Shift key and using either the arrow keys or in combination with the End key (moves to beginning/end of next block) If cells are not in a contiguous block: o Use any of the above procedures to select the first block of cells 3
o Select additional cells by holding down the Control key while clicking and dragging with the mouse o Continue selecting rows, columns, or blocks until you have selected all the cells you want 5. Operators Operator Meaning Example Arithmetic Operators + Add =3+3 - Subtract =4-3 * Multiply =3*3 / Divide =3/3 % Percent =20% ^ Exponentiation =10^2 Comparisons = Equal to A1=B1 > Greater than A1>B1 < Less than A1<B1 >= Greater than or equal to A1>=B1 <= Less than or equal to A1<=B1 Concatenate text & 6. Functions Join to values to yield one continuous text value A1 & A2 gives A1A2 Functions are similar to formulae, except they usually execute more complex operations or sets of operations, and they are native to the spreadsheet. The easiest way to become familiar with functions in Excel is to paste them into the formula bar as indicated by the arrow on the following diagram. When the function button is pressed you can select the functions either based on the most recently used or by selecting the categories of the built in functions. 4
7. Filling a Series In many instances, you will want to create a series of numbers. This is done by filling. You can fill a series quite easily: 8. Macros Give the program an example of what you want (e.g., numbers 1 through 5 in cells A1 through A5) Select the example cells and then place the cursor at the bottom-right corner of the selection The cursor will turn into a bold cross. Click and hold the mouse button while dragging down the column of cells to cell A10 Excel will extend the series down the column, showing you the current value in a small box as you go. When you have reached the desired value, release the mouse button A macro is an essentially a program that you can create by recording a series of keystrokes or other operations within the spreadsheet. Instead of performing the same task over and over again, you can record it once and then play it back to simplify the task you are doing. You create a macro using Excel s built-in macro recorder. Start the recorder by opening Tools Macro Record New Macro. The program will prompt you to name the macro and create a keyboard shortcut. The, a small window will appear with the macro recorder controls. 5
Stop Button Relative reference button The square on the left side of the button is the Stop Recording button. When you press this square, you will stop recording your macro. The button on the right is the relative reference button. By default this button is not selected so that your macro recorder assumes that the cell references you make in the course of developing your macro are absolute. 9. Random Numbers Uniform Random Variables RAND() returns an evenly distributed random number greater than or equal to 0 and less than 1. A new random number is returned every time the worksheet is calculated. To generate a random real number between a and b, use: RAND()*(b-a)+a. You can convince yourself of this by seeing that to generate a random number between 0 and 100 this formula simplifies to RAND()*100. In order to get integer random numbers between 0 and 100 use the formula =INT((RAND()*100)+0.5) of this value? Why do we need to add 0.5 before taking the integer So go ahead and type in this formula and then copy it into 10 cells you have just generated ten integer random numbers between 0 and 100. Now go into a blank cell in another column and type in the number 1 and hit return. What happened to your Random numbers. Hit the Delete key. What happened again? If you want to use RAND to generate a random number but don't want the numbers to change every time the cell is calculated, you can enter =RAND() in the formula bar, and then press F9 to change the formula to a random number. The disadvantage of this approach is that you lose the formula (try it). Instead you may want to turn off automatic recalculation (remembering that you will need to manually update the formulae when needed). To change when a worksheet or 6
workbook calculates: on the Tools menu, click Options, and then click the Calculation tab. Then under Calculation, select an option. If you select an option other than Automatic, press F9 to calculate all worksheets in all open workbooks. An alternate way to generate random numbers between two numbers is using the RANDBETWEEN(bottom,top) function. Bottom is the smallest integer RANDBETWEEN will return and top is the largest integer RANDBETWEEN will return. Try using this function. Normally Distributed Random Variables The Box-Muller method allows you to generate normal deviates with mean µ and standard deviation σ from uniform random numbers by applying the formula: NORM ( µ, σ) = µ + σ 2 ln(rand()) cos(2 * π rand()) In Excel you would use the formula =$B$2+$B$3*SQRT(-2*LN(RAND()))*COS(2*PI()*RAND()) assuming that the mean is in cell B2 and the population standard deviation in cell B3 There is not a lot of uniformity in the use of LN, LOG, and LOG10 across packages so make sure that you are specifying the natural logarithm (log e ). For PI you can substitute the value 3.14159263 if it is not available. Go ahead and set up your worksheet as above. Place the label Mean in cell a2 and Pop SD in cell A3. Now enter the values 5 and 2 in cells B2 and B3, respectively. Now enter the formula above into cell D2. Copy it and then paste it into ten cells. What is the effect of changing the mean and/or the Population SD on your distribution of random numbers? Although we have done the above manually, there are a number of other features of Excel that allow you to do a number of analyses automatically (make sure that you are confident, however, that the spreadsheet is doing what you think that it is!). 7
When the Analysis ToolPak Add-in is in place (as above) then there will be an additional entry at the bottom of the Tools entry. This will be Data Analysis entry. When you select this item from the Tools menu, the following dialog box will appear: This dialog box in turn gives you access to several analysis tools. For example, when you select the Descriptive Statistics entry and then click OK you will be presented with the following dialog: 8
We could have also generated the random numbers that we did earlier by choosing Random Number Generation from the Data Analysis Dialog and then selecting the appropriate probability distribution: The Function Wizard located on the Standard Toolbar is another method of gaining access to most of the functions contained in Microsoft Excel: In the Function Wizard, all of the available functions are arranged by category. 9