Arrays: A Powerful Excel Tool

Transcription

1 Arrays: A Powerful Excel Tool Publication Date: January 2015

2 Arrays: A Powerful Excel Tool Copyright 2015 by Mill Creek Publishing P.O. Box 11, Zionsville, IN All rights reserved. No part of this course may be reproduced in any form or by any means, without permission in writing from the publisher. The author is not engaged by this text or any accompanying lecture or electronic media in the rendering of legal, tax, accounting, or similar professional services. While the legal, tax, and accounting issues discussed in this material have been reviewed with sources believed to be reliable, concepts discussed can be affected by changes in the law or in the interpretation of such laws since this text was printed. For that reason, the accuracy and completeness of this information and the author's opinions based thereon cannot be guaranteed. In addition, state or local tax laws and procedural rules may have a material impact on the general discussion. As a result, the strategies suggested may not be suitable for every individual. Before taking any action, all references and citations should be checked and updated accordingly. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold with the understanding that the publisher is not engaged in rendering legal, accounting, or other professional service. If legal advice or other expert advice is required, the services of a competent professional person should be sought. --From a Declaration of Principles jointly adopted by a committee of the American Bar Association and a Committee of Publishers and Associations. All numerical values in this course are examples subject to change. The current values may vary and may not be valid in the present economic environment. 2 P a g e

3 Course Instructions - How to use the Materials You can review these materials on-line. You can also print the materials and read it in that format if you prefer. A glossary and Index are also provided. Review/Explanations Section The course contains Review Questions section(s) that review the materials at the end of each significant chapter. The Review Questions are an Interactive requirement of NASBA and are included to assist you in understanding the material better. The Explanations/Answers to the Review Questions sections are located at the end of the book. Student Data Files Using this manual and the accompanying exercise files you will be able to work at your own pace. The answers to each of the exercises are also in the file. Files can be found at the Course Overview page. From the Course Overview page, download the zip file to your hard drive by selecting Download Other Course Files and then double-click the zip file to extract the files. You can specify where you want Excel to put the files using the Save As command. Start Excel. Go to the File Ribbon, select Open and then find the file on your hard drive. 3 P a g e

4 Course Description: Arrays in Microsoft Excel are a very powerful, yet generally unknown tool. Using array formulas allows you to perform tasks that may currently take more than one step, and consolidate them into one step, improving efficiency. Array formulas make it easier to perform tasks such as comparing lists, mathematical operations ignoring errors, summing data using one or more criteria and finding minimums and maximums of data using various criteria. Learning Objectives Upon completion of this course, you should be able to: 1. Recognize the components of array formulas and how to apply them 2. Recognize defined range names 3. Recognize how to create an array formula using IF and functions such as SUM 4. Recognize how to compare lists using arrays 5. Identify functions such SUMPRODUCT, ISNA and ISERROR 6. Identify a crosstab Version: Excel 2003 through Excel Prerequisites: None Level: Overview 4 P a g e

5 Contents Overview... 6 What is an Array?... 6 Summary Operation... 9 Applying Constants to Arrays Using Defined Names SUM and IF in Array Formulas ARRAY with A NESTED IF SUM and IF with more than two criteria Other Related Uses More Array Uses Review Questions Comparing Lists Using ISNA Other Uses of ISERROR Other Uses of Arrays Ignoring Zeroes When Averaging Minimum and Maximum Values Finding a value in a list Crosstabs Summary Review Questions Keywords/Glossary Appendix- Named Ranges Rules for Creating Named Ranges Index Exam Questions Answers to Review Questions P a g e

6 OVERVIEW Arrays in Microsoft Excel are a very powerful, yet generally unknown tool. Using array formulas allows you to perform tasks that may currently take more than one step, and consolidate them into one step, improving efficiency. Array formulas make it easier to perform tasks such as comparing lists, mathematical operations ignoring errors, summing data using one or more criteria and finding minimums and maximums of data using various criteria. WHAT IS AN ARRAY? You will probably be surprised to realize that you have probably been using arrays and not even been aware of it. Quite simply, in Excel, an array is a block of adjacent cells that are treated as a group. It is defined as a range of data. The data can be represented in a column or row or more than one column or row. The following exercise provides a good introduction to arrays: Course Exercise: Open Array.xls and click on Initial Examples Sheet. (see instructions on page 3) You should see the data below: Think of the Row 1 as an array comprised of the numbers one through five. Row 2 also represents an array comprised of numbers one through five. What would happen if we wanted to multiply the first array by the second? I know... I know everyone knows how to multiply it. What would you do? Click in cell A3 and multiply A1 by A2 and then copy it across Correct? Yes- that is one way to do it but with an array formula you can do it so much faster as everything is calculated at once. 1. Select A3 through E3 ( the cells below the data) 2. Enter the following formula =A1:E1*A2:E2 3. Press CTRL+SHIFT+ENTER at the same time When this formula is entered, you have the following result: 6 P a g e

7 Note that the result of our formula is the same as multiplying A1*A2, B1*B2, C1*C2, D1*D2 and E1*E2 in order. Just imagine if you had not used an array and were trying to multiply 50 or 500 columns instead of 5. Arrays are very efficient. The third step is very important all array formulas must be followed by CTRL+SHIFT+ENTER. If you just hit ENTER, it will not work properly for all of the cells. Generally, only the first cell will display the correct answer and subsequent cells will not. The CTRL+SHIFT+ENTER tells Excel that the selected range, in this case A1:E1 is an array and A2:E2 is an array and they should be calculated together. LET S SEE WHAT HAPPENS WHEN WE TRY TO DELETE PART OF THE ARRAY 1. Click on Cell B3 and press the Delete key. You will get an error. 2. Click on Cell D3 and try to input a number. You will get the same error. Excel considers all of these cells to be a block so it will not perform any action that tries to separate the range of cells, such as deleting a cell or inserting a column. If you get stuck in an array and cannot get out, press the Escape key. 7 P a g e

8 Course Exercise: Open Array.xls and click on Initial Examples Sheet. THIS TIME INSTEAD OF MULTIPLYING, WE WILL ADD. 1. Select H3 through L3 ( the cells located below the data) 2. Enter the following formula =H1:L1+H2:L2 3. Press CTRL+SHIFT+ENTER at the same time The result: Note that the calculation is once again performed in order. 8 P a g e

9 SUMMARY OPERATION We can also perform summary operations on the array data as well. Course Exercise: Open Array.xls if necessary and click on Initial Examples sheet. WE WILL SUM ALL THE VALUES IN THE TWO ARRAYS 1. Click in F3 2. Type =Sum(a1:e2) 3. Press CTRL+SHIFT+ENTER This provides a result of 30, the sum of all the values in the two arrays. In this particular case, you could have left off step 3 and simply added all the cells however we have started with a very basic example so that we can build on it. Obviously, if you had left out Step 3 on our first example, the multiplication of the cells would not have worked. If you wanted the sum of the product of the two arrays, you would have typed =sum (a1:e1*a2:e2) followed by CTRL+SHIFT +ENTER: The result would be 55. Tip: You may also obtain the same answer without an array formula by using Excel s SUMPRODUCT function. This simply requires the input ranges of the two arrays and only requires you to press ENTER after the formula has been typed as SUMPRODUCT assumes the use of arrays. Now, that we have covered the basics of how an array works, let s use an array on a practical example. Course Exercise Open up Array.xls and click on Summary Example sheet. You should see the following data. We want to quickly multiply Quantity by Price to arrive at Sales Revenue (Column D). One method that everyone is familiar with is to select D2, multiply B2 * C2 and then copy it down. Obviously that works but if you had several hundred items, it would take awhile. Let s use an array and see how much more efficient a method it is. 9 P a g e

10 Course Exercise Open up Array.xls and click on Summary Example sheet. WE WILL CALCULATE SALES REVENUE FOR EACH PRODUCT BY MULTIPLYING QUANTITY AND PRICE 1. Select D2:D6 2. Type =B2:B6*C2:C6 3. Press CTRL+SHIFT+ENTER Sales Revenue should appear as follows: Now, we could add up column D to get total Sales Revenue but what if you just wanted the Total Sales Revenue and did not care about the Sales Revenue by product. You guessed it an array will do it all for you. Course Exercise Open up Array.xls and click on Summary Example sheet if necessary. WE WILL CALCULATE TOTAL SALES REVENUE FOR THE PRODUCTS BY MULTIPLYING QUANTITY AND PRICE 1. Select D7 2. Type =Sum(B2:B6*C2:C6) 3. Press CTRL+SHIFT+ENTER Notice that we did not need the values in Column D instead we multiplied Column B by Column C and summed it ALL IN ONE STEP! The same result would be obtained if we had used =SUM (d2:d6) or =SUMPRODUCT (b2:b6,c2:c6). 10 P a g e

11 However, the point here is to provide an introduction to the power of arrays in calculations and while these two calculations work here, you will see that they are not as flexible or powerful as arrays. APPLYING CONSTANTS TO ARRAYS Arrays make it easy to apply the same amount to a range of data. Within the context of the example we just used, let s assume that a commission of 5% is paid on all sales revenue. It is very easy to apply this amount to the Sales Revenue array by multiplying the entire array by 5%. To make it more interactive, we could also put the 5% in as an input cell and multiply the array by the value of the cell. Course Exercise Open up Array.xls and click on Practical Example sheet. WE WILL CALCULATE A COMMISSION BASED UPON SALES REVENUE IN COLUMN D AND OUR INPUT CELL, A7, WHICH IS THE SALES COMMISSION PERCENTAGE. 1. Select E2:E6 2. Enter this formula =D2:D6*A7 3. Press CTRL + SHIFT+ENTER Here s the result: 11 P a g e

12 Arrays make it very easy to apply a constant amount to a range of data. Notice that we did not have to worry about absolute cell references when we applied this formula since Excel considers all the cells as one. Tip: If you are not familiar with a constant or input cell, it can be extremely valuable. Constants or input cells are not unique to arrays; they can be used in many different situations. I like to use input cells when setting up budget scenarios so that I can just change a couple of assumptions and have the entire spreadsheet recalculate. It is also useful when doing what-if scenarios. I f you suddenly wanted to see the figures for a 10% commission, all you have to do is change cell A7 to 10% and all the figures automatically recalculate. USING DEFINED NAMES Our example formulas, above, would be easier if we didn t need to identify the cells within the array. Fortunately, Excel allows us to define names to identify the array. (You may be more familiar with the term range name ). Course Exercise Open up Array.xls and click on Name Example sheet if necessary. WE WILL NAME THE DIFFERENT ARRAYS USING THEIR COLUMN HEADINGS 1. Highlight A1.D6 2. Select the Formulas tab 3. Select Create from Selection located in the Defined Names group 4. Click on Create from Selection 5. Place a checkmark in Top Row and make sure that no other boxes are checked. This is because our data is organized by column and we want to use the column headings as the names of the arrays. 6. Click OK Our arrays are now named Product, Quantity, Price and Sales_Revenue. Excel used the Top Row which held the column names to name the arrays. This saved us a little bit of typing. To confirm this, click on the Name Manager if you have Excel It will show you the names and the values within that range. Names with multiple words that contain spaces are connected with a _. For more information on naming conventions, please see the Appendix. Course Exercise Open up Array.xls and click on Practical Example sheet if necessary. So, what did this do for us? 12 P a g e

13 WE WILL MULTIPLY THE ARRAYS USING THE DEFINED NAMES 1. Highlight D2:D6 2. Type = Quantity*Price 3. CTRL+SHIFT+ENTER You arrive at the same answer as typing =b2:b6*c2:c6. Obviously remembering a short name is much easier than remembering long cell ranges. Much easier! WE WILL SUM THE RESULT OF MULTIPLYING THE TWO ARRAYS NAMED QUANTITY AND PRICE 1. Select D7 2. Type=Sum(Quantity*Price) 3. CTRL+SHIFT+ENTER You obtain the same answer, $13,650 as when you typed in =SUM(b2:b6*c2:c6) Not only is it easier to type, it is much better in terms of readability. Tip If you forget to highlight the appropriate cells and only realize it after you ve pressed CTRL+SHIFT+ENTER, highlight the array and press F2 to edit the formula, then press CTRL+SHIFT+ENTER. This will also work if you accidentally press ENTER after an array formula. If you forget what you named a cell or cell, the easiest way to find the information is to click in the Name Box which is located immediately above Column A or you can press F3 to see a list of names. This works in all versions of Excel. Tip: If you wanted to actually name the arrays with something other than the column heading names, you could have selected Define Name and of course you would not have included your column headings in the selected range. I like to create my own short names as sometimes column headings are too long to remember. 13 P a g e

14 SUM AND IF IN ARRAY FORMULAS The IF statement allows you to perform an operation based on one or more conditions. This creates a very powerful tool. We ll explore using an IF statement in an array formulas with the following example data which represents an inventory of parts. Course Exercise Open up Array.xls and click on Part No. Example sheet if necessary. We have the part number, quantity on hand, cost and the quantity sold in the prior year. What we want to do is multiply the Quantity and Cost of a given part number and then sum it. One way would be to create an IF statement in Column E that tests for 1 in the Part No. column and then sum it. Obviously, there is a faster and more efficient way to do that using arrays. Course Exercise Open up Array.xls and click on Part No. Example sheet if necessary WE WILL MULTIPLY THE COST AND QUANTITY IF THE PART NO. IS 1 AS THE FIRST STEP. Let s start by multiplying the cost and quantity for all items that are Part No. 1. We can do this all in one step by nesting the array formulas within the IF statement. We know that the syntax of the IF statement is =IF (logical test, value if True, value if False). So, if the Part No. is equal to 1, we want to calculate the extended cost (multiply Quantity by Cost). This would be accomplished using the following formula: =if (a2:a10=1,b2:b10*c2:c10). 1. Select D11 to display the answer 2. Type =IF(A2:A10=1,B2:B10*C2:C10) 3. Press CTRL+SHIFT+ENTER 14 P a g e

15 This only gave us the extended cost for the first Part No. 1 as Excel only calculated 50*3, which is the first row. If Row 2 had displayed another Part No., we would have received an answer of FALSE. Obviously, not what we are looking for. We need to add another function so that Excel understands that we want it to look at the entire array. The SUM function allows us to add data. So, if we added a SUM to our existing IF statement, it would say that if the Part No. was equal to 1, then multiply the two arrays together and summarize the results of that multiplication. Course Exercise Open up Array.xls and click on Part No. Example sheet if necessary WE CREATED A FORMULA FOR MULTIPLYING QUANTITY AND COST FOR PART NO. 1 NOW WE NEED TO SUM IT 1. Select Cell D11 again 2. Type =Sum(IF(A2:A10=1,B2:B10*C2:C10)) - ( or simply edit the earlier formula if it is still displayed) 3. Press CTRL+SHIFT+ENTER You obtain a result of 725. This represents the extended cost of all the Part No. 1 s in the data. Looking at the formula, we said that if the range a2:a10 equaled 1, then multiply the corresponding values in b2:b10 and c2:c10 and then sum the results of the multiplied values. All in one step! Let s try something a little different using the same data EXAMPLE 2- WE WILL SUM PRIOR YEAR SALES IF QUANTITY IS 0 Let s assume that you want to know the quantity of product on hand for which the Prior Year Sales quantity was Click in cell D13 2. Type =Sum(IF(D2:D10=0,B2:B10)) 3. Press CTRL+SHIFT+ENTER 15 P a g e

16 You obtain a value of 225 which is the total quantity for which Prior Year Sales were 0. This also happens to be the quantity of Part No. 2. EXAMPLE 3: WE WILL DETERMINE WHAT THE TOTAL COST IS IF THE PRIOR YEAR SALES QTY WAS 0 If you wanted to know the extended cost of the parts for which there was no prior sales quantity, type the following formula: 1. Click in cell D14 2. Type =SUM(IF(D2:D10=0,B2:B10*C2:C10)) 3. Press CTRL+SHIFT+ENTER Your result is 2,000 which is the Quantity multiplied by the Cost of the Parts whose PY Sales Quantity was zero. Tip In some instances, SUMIF will also accomplish the task. SUMIF is good for returning the sum of one array given a specified condition for example, determining the total quantity that had zero PY Sales Quantity. However, SUMIF will not work for the immediately preceding example of multiplying Quantity and Cost if prior year sales are zero since SUMIF usually just sums data. An alternative way to accomplish this task would be to use the SUMPRODUCT function. This function multiplies corresponding components in the given arrays, and returns the sum of those products. Since it assumes the components are arrays, you do not need to press CTRL+SHIFT+ENTER. 16 P a g e

17 EXAMPLE 4: WE WILL DETERMINE WHAT THE TOTAL QUANTITY IS IF COST IS LESS THAN OR EQUAL TO $10 Now, let s make the example a little bit more complicated. Assume that you need to know the total Quantity on hand of inventory for which the Cost is less than or equal to $ Select D17 2. type: =SUM (IF(C2:C10<=10,B2:B10)) 3. Press CTRL+SHIFT+ENTER Your result is 400. This formula is saying that if the cost is less than or equal to $10, then sum the related values in the Quantity array. 17 P a g e

18 ARRAY WITH A NESTED IF In the next example, we want to know the Quantity on hand for parts where the Cost is greater than or equal to $10, but less than or equal to $20. This will require the use of nested IFs. A nested IF is when an IF statement is placed inside another IF statement. Typically this is used if you wanted to test for 3 conditions or more since a simple IF only tests for two conditions a True and a False. A nested IF statement can continue the value if True with another IF Statement. So, essentially you re saying IF this is True OR IF another logical test is True, then return a value if True. Let s go through a simple example. Assume that you have 5 different color sweaters. If the sweater is red it is On Sale, If the sweater is blue it is On Clearance ; otherwise, it is Regular Price. We tested for three different conditions red, blue, other. If the sweater was red or blue then a True Condition was met and it was assigned either to be On Sale or On Clearance. If neither condition was true, then it was False and would default to being Regular Price. You are not just limited to nesting one IF function within another. In Excel 2003, you can nest up to 7 and in Excel 2007, you can nest up to 64 IF functions. Course Exercise Open up Array.xls and click on Part No. Example sheet if necessary WE WANT TO SUM THE QUANTITY WHERE THE COST IS BETWEEN $10 AND $20 INCLUSIVE 1. Select D18 2. Type =SUM(IF(C2:C10>=10, if (C2:C10<=20,B2:B10))) 3. Press CTRL+SHIFT+ENTER The resulting answer is P a g e

19 This more complex, nested formula is saying that if the Cost in that array, Column C, is greater than or equal to $10 and the Cost is also less than or equal to $20 (both are True), then sum the related Quantity in that array. EXAMPLE 2: WE WILL DETERMINE THE EXTENDED COST OF ALL ITEMS IF COST IS BETWEEN $10- AND $20 INCLUSIVE How would you calculate the extended cost of all items on hand for which the cost is greater than or equal to $10 and less than or equal to $20? This formula will be constructed in the same manner as the above formula except that if both IF statements are true, the result will be b2:b10*c2:c10, which is Quantity multiplied by Cost. 1. Select D19 2. Type =SUM(IF(C2:C10>=10,if(C2:C10<=20,B2:B10*C2:C10))) 3. Press CTRL+SHIFT+ENTER The result is 1,250. Once again, this result is arrived at by the formula looking for Costs greater than or equal to $10 and less than or equal to $20 and, when the conditions are true, multiplying the related Quantity by the related Cost. Tip You can also use the SUMIFS function, which is available in Excel 2007, to sum data using multiple criteria. To arrive at the quantities on hand for which the cost is greater than or equal to $10 and less than or equal to $20, your formula would be Below is how the formula breaks down if you use the Function Wizard and SumIFs. Please note, you would be unable to perform the array multiplication used in the immediately preceding example as SUMIFs only sums data. 19 P a g e

20 SUM AND IF WITH MORE THAN TWO CRITERIA EXAMPLE 3: WE WILL DETERMINE WHICH QUANTITIES ON HAND ARE BETWEEN $10 AND $20 INCLUSIVE FOR PART NO. 2. Using the same data, let s assume that you need to know by part number which quantities on hand are greater than or equal to $10 and less than or equal to $20. We ll start with part number 2. The formula will use the same nested IF statement used above, except that it will have one more nesting level. 1. Select cell D20 2. Type =SUM(IF(A2:A10=2,if(C2:C10>=10,if(C2:C10<=20,B2:B10)))) 3. Press CTRL+SHIFT+ENTER This is essentially the same formula as in the previous example. Breaking it down, it says that if the Part No. equals 2- if this is True- and if the Cost is greater than or equal to 10 is True and if the Cost less than or equal to 20 is True, then sum the related Quantity in the array. Otherwise, don t do anything. The result of this formula is 75. Once again, you could obtain this same result with SUMIFS. However, the array gives you greater flexibility. Remember you can always use defined names to simplify your work with arrays. OTHER RELATED USES We ve been focused on SUM and IF. However, the logic also applies to AVERAGE and AVERAGE and IF. The formula configuration is the same. You would start with an IF statement, then add AVERAGE to it. Excel 2007 also offers a new function called AVERAGEIF and AVERAGEIFs. 20 P a g e

21 MORE ARRAY USES Many times, you have a need to know if something has changed by more than a certain amount. As an example, if you have input new inventory standard costs into your costing system, you may want to perform a sanity check to see which standard costs have changed by more than a specified amount. Auditors are also interested in certain changes above a tolerable error level. Course Exercise Open up Array.xls and click on Inventory Std. Cost Example sheet We ve already concluded that arrays are very useful for comparing related data. Let s work with the following inventory standard cost data and assume that we need to identify those items for which the standard cost has changed by more than $2. WE WILL IDENTIFY THOSE ITEMS FOR WHICH THE STANDARD COSTS HAVE CHANGED BY MORE THAN $2 One way to do this would be to use Column D and subtract Std Cost 2 from Std Cost 1, then, in Column E, use an IF statement to identify those differences that are greater than 2, but that is cumbersome for a lot of data. A more efficient way is below. 1. Select D2:D9 an empty range at the moment 2. Type =IF(ABS(C2:C9-B2:B9)>2,abs(C2:C9-B2:B9), ) 3. Press CTRL + SHIFT+ENTER You obtain the following: 21 P a g e

22 Now, when you scan the list, you are only presented with those items that meet your criteria. In this case, 3 items had a variance greater than 2: Item A, Item E and Item G. Wondering what that ABS is in the formula? The ABS function returns the value without its sign. In other words, it will show variances that are greater than 2 and variances greater than -2. The at the end of the IF indicates that Excel should display a blank cell if that condition is met. 22 P a g e

23 REVIEW QUESTIONS Review questions are required by NASBA and are designed to assist in the learning process. These questions are NOT graded. Answers can be found at the end of the EBook. 1. In Excel, an array is: a. A block of adjacent cells that are treated as a group b. Only data organized in a column c. Only data organized in a row d. Limited to two adjacent cells 2. Which of the following is correct: a. An array formula must be followed by the ENTER key b. An array formula must be followed by CTRL+SHIFT+ENTER c. To delete part of an array, just hit the Delete key d. Defined names must be used for array formulas to work 3. The SUMPRODUCT function: a. Returns the sum of the products of two or more arrays b. Must be followed by CTRL+SHIFT+ENTER c. Requires an IF statement d. Is limited to three arrays 4. What does the ABS function do? a. It returns the value of a number without its sign b. It prevents the cell from being locked c. There is no such thing as an ABS function in Excel d. It formats a number with a $ sign 23 P a g e

24 COMPARING LISTS A great feature of arrays is the ease with which you can compare two lists. There are a number of reasons that you may want to compare lists. You may wish to see which items are present on both lists or which items do not appear on both lists. Course Exercise Open up Array.xls and click on List Compare sheet Let s assume that you have an inventory list by item that contains quantity on hand. On another list, you have all the items that have sold in the past year. The two lists are presented below: To determine if there s a potential inventory obsolescence problem, you want to identify those items which have not sold in the past year and sum the quantities on hand. Let s break this into steps: 1. We need to match the two lists of items to see which items appear on one list but not the other. 2. Once, we have determined which items match, we can then sum up the associated quantities. We need to compare the two arrays of Items to determine which ones are on the list of items on hand and not on the list of items sold in the prior year. To accomplish this, we ll use the Match function. The Match function is an Excel lookup function and is organized so that you provide a value or an array to compare against, then the type of match you want (either an exact match, less than or equal to or greater than or equal to). The result of the Match function is the order in the array in which the matched item resides. So, if there s a match on item B in the Items Sold PY array, the result would be 1 as item B is the first on the list. Let s just look at the list and visually match it, Item B is the 1 st match, Item D is the 2 nd, followed by Item F and Item H. We should expect the Match function to find and number the items in the same manner as just did visually. 24 P a g e

25 Course Exercise Open up Array.xls and click on List Compare sheet WE WILL COMPARE THE 2 LISTS AND THEN MATCH UP ITEMS THAT APPEAR ON BOTH LISTS 1. Select C2:C9 2. Type =MATCH(A2:A9,F2:F9,0) 3. Press CTRL+SHIFT+ENTER This is telling Excel to match the array of Items in Column A, Item, with the array of Items Sold PY, in Column F and return a value if there s an exact match. The result below matches what we visualized. Where there was not a match a #N/A error value appears. The #N/A indicates that there was not match - that these items did not have a sale in the prior year. 4 items did not have a match and are so shown with the #N/A error value. This gives us what we were looking for. Now, the question is how we use the #N/A error code in a way that helps us. Excel has provided a way to identify if there s an error value. It is the ISERROR formula. This formula checks a cell s contents to determine whether there is a #N/A, #VALUE, #REF, #DIV/0, #NUM or #NAME and, if there is, returns a value of True and, if there s no error value, returns a value of False. Since the IF statement in Excel works off of True or False values, we can use a combination of these two formulas to our advantage. If we typed =ISERROR(C2), the formula would return a value of True because C2 contains an error value. If we typed =ISERROR(C3), the formula would return a value of False because C3 does not contain an error. If we typed =ISERROR(c2:c9) this formula would return a value of True. Why? Because there are errors in that array. We ve already learned that the syntax of the IF statement is IF(logical test, value if True, value if False). So, we want to sum quantities for which there is an error. We add a SUM and IF to the ISERROR test to 25 P a g e

26 accomplish this. Sound complex? Once you have done this a couple of times, you won t think so. To simplify, we are telling Excel to check and see if there is an error value in Column C and if there is then to sum the corresponding values in Column B- Quantity. Course Exercise Open up Array.xls and click on List Compare sheet WE WILL CHECK COLUMN C FOR ERROR S AND HAVE EXCEL SUM THE CORRESPONDING VALUES IN COLUMN B. 1. Select cell B10 2. Type =SUM(IF(ISERROR(C2:C9),B2:B9,0)) 3. Press CTRL+SHIFT+ENTER This formula finds that cells that have an error value (value is True) and sums the corresponding cells in column B (Quantity) for which there s an error. The total Quantity for which there were no sales in the prior year is 375. Visually, you can see this in the screen shot above If we had unit costs, we could use arrays to determine the extended cost of those items in inventory that had no prior year sales as well. Other uses of this formula could be to compare vendor lists to vendors from whom a purchase had been made in the prior year to delete inactive vendors or to compare approved customers to sales data to ensure that all customers are approved. 26 P a g e

27 USING ISNA Sometimes, you just want to know if all items on one list are on the other and don t want to review all the detail if it is not necessary. Note, above, that any item that doesn t match is indicated by #N/A. The ISNA function checks for a returned value of #N/A and returns TRUE if a #N/A is returned. Assume that we wanted to compare the approved customer master list to a listing of sales by customer. Any customer on the sales list that is not on the approved customer master list may be a fraudulent sale. Rather than just using the Match function, which requires that we scan the data, we could use the ISNA function to quickly determine whether there are any unmatched items as well as count the number of unmatched items. In this example, we ll compare a simple customer master list to a sales list using ISNA. In cell b12, type =ISNA(match(a3:a10,b3:b10,0)) CTRL+SHIFT+ENTER If an item in the sales file is not in the customer master, this will return TRUE. The order is important. Note that if we compared the customer master to the sales file, a value of FALSE would be returned as all items in the customer master are in the sales file. 27 P a g e

28 So, the question is whether there is a #N/A returned. That answer is TRUE. There are items in the sales file that do not appear on the customer master. How many items are there? In cell B13, type the following: =SUM (1*ISNA(MATCH(a3:a10,b3:b10,0))) CTRL+SHIFT+ENTER This will accumulate the number of #N/A s in the comparison. 28 P a g e

29 There are 4 instances of unmatched items. In this example, there could be 4 potential unapproved customers. ISNA provides a quick and easy way to compare lists by identifying the existence of #N/A in the MATCH comparison and provides the ability to easily accumulate the number of unmatched items. 29 P a g e

30 OTHER USES OF ISERROR Those pesky error values can really make your life miserable because they prevent you from performing normal operations on data. If you have a very long column of data that you just want to sum and there s a #DIV/0 or other error code in the column, you can t sum the data. This generally results in a long and tedious process of going through the data and visually identifying the error value and either deleting the error or changing it to a zero. Sometimes you want to know if there is an error value. Sometimes you don t care. You can use an array formula to sum data ignoring the errors. Let s use a simple example: Course Exercise Open up Array.xls and click on Sum and Average Ignore Errors sheet WE WILL SUM A COLUMN OF NUMBERS THAT INCLUDES AN ERROR VALUE 1. Select A5 2. Type =Sum(A1:A4) 3. Press Enter The result is #N/A. Excel will not allow you to add up a column of numbers if there is an error value in the column. WE WILL SUM A COLUMN OF NUMBERS THAT INCLUDES AN ERROR VALUE BY REPLACING THE ERROR VALUES WITH A ZERO. Let s try it again. 1. Select A5 2. Type =sum(if(iserror(a1:a4),0,a1:a4)) 3. Press CTRL+SHIFT+ENTER 30 P a g e

31 This time, Excel replaced the error value with a zero and added up the values so that the result displayed is 40. It is important to note that Excel considers cell A3 to be a 0 instead of a blank cell. This would be a problem if you had wanted to Average instead of Sum. When dealing with large spreadsheets, error values can be very frustrating. You may want to know if any error values exist in the data before working with it. Arrays provide a quick method to make this determination. Using the above example: In cell A5 type =sum (iserror(a1:a4)*1) CTRL+SHIFT+ENTER This will accumulate the number of instances of an error code. The result in A5 is 1. There is one instance of an error in the data. This will work with any error value (#N/A, #DIV/0,#NUM!,#NAME?,#VALUE!,#REF!,#NULL!) 31 P a g e

32 OTHER USES OF ARRAYS Ignoring Zeroes When Averaging Sometimes there are zeros in data and you want the average, excluding the zeros as you know they are errors. If you use the AVERAGE function, it will use the zeros in calculating the average. Obviously, this can really skew your average. The good news is that we can use an array formula to average the data and ignore the zeros. Once again, the answer lies in the IF function. We want to take an array and average the data only if the data is not equal to zero. The data is shown below: Course Exercise Open up Array.xls and click on Sum and Average Ignore Errors sheet WE WILL AVERAGE A COLUMN OF NUMBERS AND IGNORE ANY ZEROS IN THE COLUMN 1. Select C5 2. Type =AVERAGE(if(C1:C4<>0,C1:C4)) 3. Press CTRL+SHIFT+ENTER This formula tells Excel to average the data that is not equal to zero. The result is , which is 40 divided by 3 (the three numbers that are not equal to zero). The <> symbol of Not Equal can be very useful. Minimum and Maximum Values You can also easily find minimums and maximums using arrays. By using the MIN and MAX functions in Excel, you can find the largest or smallest number in an array or a subset of an array. 32 P a g e

33 Course Exercise Open up Array.xls and click on Min Max sheet WE WILL DETERMINE THE MINIMUM INVOICE AMOUNT We can use the MIN functions on the array of invoice amount in cells B2:B10 to determine the minimum invoice amount 1. Select B11 2. Type =MIN(B2:B10) 3. Press CTRL+SHIFT+ENTER The resulting answer is 50. The maximum invoice amount would be =MAX(b2:b10) CTRL+SHIFT+ENTER. The maximum is 125. Now, if you are familiar with the Min and Max function, then you know in this case we did not need to do CTRL+SHIFT+ENTER. If we had simply typed =Min(B2.B10) and pressed Enter, we would have received the same answer. However, we want to take this a bit further and find the minim and maximum by customer #, which is why we used an array with Min and Max in the exercise above. Assume that we want to know the minimum invoice for specific customer. WE WILL DETERMINE THE LOWEST INVOICE AMOUNT FOR CUSTOMER Select B12 2. Type =MIN(if(a2:a10=123,b2:b10)) 33 P a g e

34 3. Press CTRL+SHIFT+ENTER. The result is 50, the minimum value for customer 123. WE WILL DETERMINE THE HIGHEST INVOICE AMOUNT FOR CUSTOMER 123 The maximum value for customer 123 would be done in the same way. 1. Select B13 2. Type =MAX(IF(A2:A10=123,B2:B10)) 3. Press CTRL+SHIFT+ENTER The result is 100, the maximum invoice for customer 123. Tip the above syntax also works with the AVERAGE function. To find the average invoice for customer 123, type =AVERAGE(if(a2:a10=123,b2:b10)) CTRL+SHFT+ENTER. The answer is Finding a value in a list You may compare a single cell array to a multiple cell array to determine if the single cell value appears in the larger array. Here s an example: You want a formula in D1 that will indicate whether the value typed in cell C1 is in the list or not in the list. In cell D1, type the following: =if(or(c1=a4:c7), In the list, Not in the list ) CTRL+SHIFT+ENTER 34 P a g e

35 This formula compares C1 to all the values in A4:C7 to determine whether it is found. If the IF expression is TRUE (a corresponding value is found), it returns In the list. If the IF expression is FALSE, it returns Not in the list. The OR is required because we want to know if there are any matches. Without the OR, we would be evaluating whether C1 matched everything on the list. After typing the formula, input Dress in C1. It should indicate that Dress is In the list. Crosstabs If you use Pivot Tables, you ve used crosstabs. You can use array formulas to create crosstabs, however, most of the time you will want to use a pivot table. Crosstabs are useful if you want to extract certain data. Here s an example: Assume that we want to accumulate amount by customer and by product. To make it easier, let s name the arrays based in their headings. So, A2:A7 would be Customer, B2:B7 will be Product and C2:C7 will be Amount. We will use the Formulas tab and Create from Selection in the Defined Names Group to do this. The creation of the Customer name is shown below: (This is also on Page 11 of the course if you want a refresher) 35 P a g e

36 Do the same for Product and Amount. Now, Customer refers to A2:A7, Product refers to B2:B7 and Amount refers to C2:C7. Let s start in cell E1 and type Customer, in cell F1 type Cookies and in cell G1 type Cakes. Also, in E2:E4, let s type the customers that we re interested in. In this case, 123 goes in E2, 456 goes in E3 and 789 goes in E4. Now for the array formulas. In cell F2, type =sum(($e2=customer)*(f$1=product)*amount) CTRL+SHIFT+ENTER This is telling Excel to sum amount if the Customer array equals 123 and the Product array equals Cookies. 36 P a g e

37 Why are we using absolute cell references in front of column E and row 1? We re going to copy this formula across and down. So, when we copy it across, we want column E (Customer) to remain the same. When we copy down, we want row 1 (Product) to remain the same. Here s the result of the formula in F2: Here s the result after we copy it across and then down: Congratulations. You ve just created a homemade pivot table using an array formula. 37 P a g e

38 SUMMARY Array formulas are very powerful tools that can be more efficient than traditional methods. They are also useful when handling large amounts of data. This course is only an introduction to the uses of arrays. There are many more advanced possibilities with this Excel tool. There are many Excel functions such as FREQUENCY and SUMPRODUCT that use arrays. Below is an example using the FREQUENCY function. A frequency distribution allows you to measure performance of one item against others. A good example would be a comparison of students in a class and the grade category that they fall into. Again, consider tracking returns of an item by color or even item number. Other possibilities include a breakdown of prices for a product line or even ages or education of your workforce. A frequency distribution is a table where data in a spreadsheet is counted into bins. It is a good habit double check your calculation - to verify that the number of items in your input range equals the number of observations in your answer. Use a COUNT function on the input range and the sum function on your answer. To view the worksheet, open Frequency-salary.xls In this example, we want to see how many employees are making more than 50, in salary. 1. Create a set of numbers to use as bins. Keeping with our example below, we are going to create two (2) bins- one for 50,000 and under and one for over 50,000. The description in Column D is solely for clarification and documentation and is not used in the calculation. 3. Select the cells where you want your answer to go. In this case, select F10.F11 38 P a g e

39 3. Type = Frequency (and then select the input range. In this case you would select B9.B Type in a comma and then select your bin range. In this case E10.E Type a closing parenthesis (. Your formula should look like =frequency (B9.B26.E10.E11) 6. Now the important part - press CTRL+SHIFT+ENTER. The resulting frequency distribution should appear and resemble Column G. The resulting formula should look like So, what does this tell you? It tells you that 7 people make over $50,000. A couple of comments: Excel puts the brackets around the formula to show that it is an array. If at step 2, you only selected F10 and after going through the other steps, you copied the formula down- the answer would be wrong, Because this is essentially an array formula, you need to select all the cells at one time for this to work. Also, bins must be numeric. As mentioned above, it is a good idea to sum your Frequency and then count your observations to make sure that the number are the same. In the example below, my frequencies total 18. If I counted the number of people in my data, it should total 18 people otherwise there is a problem somewhere 39 P a g e

40 REVIEW QUESTIONS Review questions are required by NASBA and are designed to assist in the learning process. These questions are NOT graded. Answers can be found at the end of the EBook. 5. The Match function: a. Returns the relative position of an item in an array that matches a specified value b. Returns TRUE or FALSE depending on whether an item matches an item in an array c. Only works with an exact match d. Returns the matching value 6. The ISNA function: a. Checks a cell s contents to determine whether there s a #N/A,#VALUE,#REF,#DIV/0,#NUM,#NULL or #NAME b. Returns a value of TRUE if there is a #N/A error value c. Is not an Excel function d. Has the same use as the ISERROR function 7. One way to have Excel ignore zeros when averaging numbers is to: a. Use the IFZERO function b. Use the IFAVERAGE function c. Use an array formula with the AVERAGE function combined with the IF function d. Use the AVERAGE function 8. To sum a column of numbers with errors in it, one way would be to: a. Use the ISERROR function b. Use an array formula with the SUM function combined with the IF function combined with the ISERROR function c. Use an array formula with the SUM function d. Use the SUM function 40 P a g e

41 KEYWORDS/GLOSSARY Absolute Cell Reference- A cell that does not move even when a formula referencing it is copied down or across. Array An arrangement or order; a block of related data elements Array formula Formula that works with an array or series of data values rather than a single data value. Constant- a fixed cell reference Defined Name- Naming a cell or cells so that the name rather than the cell address can be used Frequency Distribution- Is a method t o summarize groups of data and to determine the number of occurrences in the group. It is useful to determine results of an election, salaries in an organization, sales of a product within a certain period etc.. IF Function- An Excel logical function. It tests a cell or cells to determine if the condition specified is True or False Inclusive It includes the inner and outer parameter values between 1 and 5 inclusive means that 1 and 5 would be included in the group ISNA Checks for the #N/A (value not available) error and returns a TRUE if found. ISERROR An Excel information function. It tests for error values ((#N/A, #VALUE!, #REF!, #DIV/0!, #NUM!, #NAME?, or #NULL) and returns a True. Min- An Excel function that calculates the Minimum (lowest) value found Match An Excel lookup function. Returns the sum of the products of corresponding array components Max An Excel function that calculates the Maximum (highest) value found Nested IF- An Excel IF is placed inside another IF Function to test for more than 2 conditions Sum Product - Returns the sum of the products of corresponding array components. 41 P a g e

42 APPENDIX- NAMED RANGES Rules for Creating Named Ranges Names must begin with either a letter or an underscore. Only letters, numbers, underscores and periods can all be used after the first character. Spaces cannot be used. Correct Name Total_Expense Net_Income Incorrect Name Total-Expense Net Income Year Be aware if you use Excel 2007/2010 or 2013 that the spreadsheet is a lot bigger. For example, TAX09 would actually be a cell reference and should not be used as a range name. 42 P a g e

43 INDEX ABS, 22 Array, 5 AVERAGEIF, 20 AVERAGEIFs, 20 Comparing Lists, 23 Constants, 10 Crosstabs, 34 CTRL+SHIFT+ENTER, 6 Defined Names, 11 FREQUENCY, 37 IF function, 18 ISERROR, 24, 29 ISNA, 26 Maximum, 31 Minimum, 31 range name, 11 SUMPRODUCT, 16, 37 Zeroes, P a g e

44 EXAM QUESTIONS 1. When using a defined name for an array: A. Column headings are the only option for defined names B. Column headings may not be used as a defined name C. You must define a name using the formulas tab and selecting Define Name D. You may use either column headings or define a different name 2. Which would be a valid defined name? A. 2009_Sales. B. Price_2009. C. 3CGS. D. Sales If A2:A10 contains a state abbreviation and B2:B10 contains sales to the various states, which of the following array formulas will sum all sales to Indiana (IN)? A. =SUM(IF(A2:A10= IN,B2:B10)) B. =IF(A2:A10= IN,=SUM(B2:B10)) C. =SUM(B2:B10) D. =IF(SUM(A2:A10= IN,B2:B10)) 4. Using the facts in Question 3 above, how would this be done using SUMPRODUCT? A. =SUMPRODUCT(B2:B10) B. =SUMPRODUCT((A2:A10= IN )*(B2:B10)) C. =SUMPRODUCT(IF(A2:A10= IN,B2:B10)) D. =IF(A2:A10= IN,SUMPRODUCT(B2:B10)) 5. Which of the following represents a nested IF array that will work in Excel? A. =IF(A2:A10= IN, YES, NO ) B. =SUM(IF(A2:A10= IN,IF(B2:B10>500,IF(B2:B10<1000,B2:B10)))) C. =SUM(IF(A2:A10= IN,IF(B2:B10>500),IF(B2:B10<1000),B2:B10)) D. =IF(A2:A10= IN,B2:B10>500,B2:B10<1000,SUM(B2:B10)) 6. To compare lists, you would want to use the function as part of the array formula. A. SUMPRODUCT B. INDEX C. MATCH D. ABS 7. In the array formula =MATCH(A2:A9,F2:F9,0), what is displayed if there is not a match? 44 P a g e

45 A. #N/A B. ISNA C. ISERROR D. The corresponding order in the array being matched 8. ISERROR by itself A. Checks for error values in a cell B. Deletes error values in a cell C. Creates an error value in a cell D. Ignores error values in a cell 9. To determine the lowest invoice amount for customer 789 in Min and Max Sheets, you would use the following formula: A. =MAX(if(a2:a10=789,b2:b10)) B. =MIN(if(a2:a10=789,b2:b10)) C. =LOWEST(if(a2:a10=789,b2:b10)) D. =LESSER(if(b2:b10=789,a2:a10)) 10. Crosstabs are most similar to: A. Data Tables B. Tables C. Pivot Tables D. Scenarios 11. What will this array formula accomplish: =sum(if(iserror(a1:a4),0,a1:a4)) A. It will provide the sum of cells a1:a4 even if there is an error value in one of the cells B. It will accumulate the number of error values in cells a1:a4 C. It will tell you if there are any #N/A error values in a1:a4 D. It will accumulate the number of #N/A error values in cells a1:a4 12.What will this array formula accomplish: =sum(iserror(b1:b4)*1) A. It will tell you if there are any #N/A error values in cells b1:b4 B. If will sum the number of error values in cells b1:b4 C. It will sum the number of #N/A error values in cells b1:b4 D. It will return TRUE if there are any error values in cells b1:b4 13.What will this array formula accomplish: =sum(1*isna(match(a3:a10,b3:b10,0))) A. It will return TRUE if there are any error values in a3:b10 B. It will accumulate all error values in a3:b10 C. It will sum the number of #N/A error values resulting in the comparison of a3:a10 to b3:b10 D. It will result in a value of 1 45 P a g e

46 ANSWERS TO REVIEW QUESTIONS 1. In Excel, an array is: a. Correct. An array is a block of adjacent cells that are treated as a group. It is not confined to a single row or column. b. Incorrect. Data organized in a column could be an array, but an array is not confined to just columns. It could also be a row or consist of both columns and rows. c. Incorrect. Data organized in a row could be an array, but an array is not confined to just rows. It could also be a column or consist of both rows and columns that are in adjacent cells. d. Incorrect. An array may be more than two adjacent cells. The number of cells in an array may be more limited by computer memory than by Excel. A safe maximum number of cells to use is around 65, Which of the following is correct: a. Incorrect. If you just hit the ENTER key, the array formula will not work properly for all the cells in the array. b. Correct. Excel requires that an array formula must be followed by CTRL+SHIFT+ENTER c. Incorrect. When you hit the Delete key for a defined array, you will receive an error message that says You cannot change part of an array. d. Incorrect. Defined range names are a great tool to use within array formulas, but are not required. Array formulas will work without defined range names. 3. The SUMPRODUCT function: a. Correct. Excel is programmed such that the SUMPRODUCT function returns the sum of the products of two or more arrays b. Incorrect. Even though the SUMPRODUCT function uses arrays, it need only be followed by ENTER c. Incorrect. The SUMPRODUCT function does not require an IF statement. However, using SUM(IF( will accomplish the same thing d. Incorrect. SUMPRODUCT can handle up to 30 arrays. 4. What does the ABS function do? a. Correct. It returns the absolute value of a number. The absolute value is a number without its sign. b. Incorrect. The ABS function has nothing to do with preventing the cell from being locked. This is done using the Format button on the Home tab. c. Incorrect. There is an ABS function in Excel that returns the value of a number without a sign d. Incorrect. This is accomplished by using the $ button on the Number section of the Home tab or by using the Format button in the Cells section of the Home tab. The ABS function returns the value of a number without a sign. 5. The Match function: 46 P a g e