Larry sent me a list of 12 beautifully defined rules for making better spreadsheets with this comment:
I thought I would share with you a set of “rules” for building spreadsheets. I developed these over many years of financial analysis and reviewing the work of other analysts.
His rules are not only comprehensive, but valid for all types of spreadsheets, not just financial models. Here is the complete list:
- Most important rule: never start a spreadsheet without first being able to define in one sentence or less why you are creating the spreadsheet.
- Second most important rule: a spreadsheet should explain itself. Six months from now, someone else will not be able to tell what you were thinking when you created the spreadsheet. You may not even remember your own thoughts as to why you created it. A well-defined spreadsheet should justify its own existence.
- Every spreadsheet should have a title. This should help explain “second most important rule” and allow the reader to understand what they are looking at.
- The footnote section of a spreadsheet should include the path/filename/date and creator’s name.
- Audit trail: whenever possible, formulas should be used in the spreadsheet rather than inputting numerical values. This way you, or someone else, can follow the logic of the spreadsheet.
- Assumptions: mathematical assumptions should be identified in separate cells, not buried within formulas. That way they can be printed out as required. It is very easy to forget that you have a formula that says (C5 X 200). If instead, it says (C5 X D7) and then D7 shows 200, it is less likely to forget what assumptions are included in the spreadsheet.
- Assumptions: document your assumptions. If you’re increasing a value by an inflation rate, make note that this is an inflationary increase. A few words to the right hand side of a cell can save many hours of hunting and digging at a later date.
- Unless your data source is obvious, you should document where you obtained your data. A few words to the right hand side of a cell can save many hours of hunting and digging at a later date. (Yes, you read that in the last bullet as well).
- Presentation format: all spreadsheets, should be designed so that it is easy to follow the process flow and result. Almost every spreadsheet should be presentable and understandable to senior management without additional formatting or explanation. (tips: how to design boss-proof excel sheets)
- It is okay to add notes, procedures steps or other explanations in text format within your spreadsheet. Any guidelines provided to the next person who looks at or works on the spreadsheet will be highly appreciated.
- Learn to use the intermediate level functions within Excel. These include: sum, sumif, macro’s, logic (if, then, else), auto sum, filtering, auto subtotal, sorting, charting, pivot tables, auto formatting, conditional formatting and formula auditing. None of these functions are at advanced level or particularly difficult. If you need help on how to use them; please ask someone else in the department, use the Excel help function, or look up the function on the web. The use of these functions will save you a great deal of time and make your spreadsheets more accurate.
- Do the common sense test. Look at the spreadsheet as though you didn’t create it. Does it answer the question asked? Can you follow the logic? Does the result seem OK? If all this is yes, then ask what decision will be made from knowing this information. If you can’t answer this, go back to step one.
If we summarize all these rules in one sentence, it will be,
Your spreadsheet should have a purpose, it should be well documented & easily understandable and you should make use various features in Excel to achieve this.
Download Larry’s Rules for Better Spreadsheets Poster:
I took the liberty of putting all these 12 rules in small poster. Take a print and stick near your workspace to remind you how to make better spreadsheets.
Download it here [PDF].
Additional Material on Making Awesome Spreadsheets:
Thank you Larry
Thank you so much for sharing these rules with all of us Larry. I am sure our readers are going to dig this one 🙂
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13 Responses to “Using pivot tables to find out non performing customers”
To avoid the helper column and the macro, I would transpose the data into the format shown above (Name, Year, Sales). Now I can show more than one year, I can summarize - I can do many more things with it. ASAP Utilities (http://www.asap-utilities.com) has a new experimental feature that can easily transpose the table into the correct format. Much easier in my opinion.
David
Of course with alternative data structure, we can easily setup a slicer based solution so that everything works like clockwork with even less work.
David, I was just about to post the same!
In Contextures site, I remember there's a post on how to do that. Clearly, the way data is layed out on the very beginning is critical to get the best results, and even you may thinkg the original layout is the best way, it is clearly not. And that kind of mistakes are the ones I love ! because it teaches and trains you to avoid them, and how to think on the data structure the next time.
Eventually, you get to that place when you "see" the structure on the moment the client tells you the request, and then, you realized you had an ephiphany, that glorious moment when data is no longer a mistery to you!!!
Rgds,
Chandoo,
If the goal is to see the list of customers who have not business from yearX, I would change the helper column formula to :
=IF(selYear="all",sum(C4:M4),sum(offset(C4:M4,,selyear-2002,1,columns(C4:M4)-selyear+2002)))This formula will sum the sales from Selected Year to 2012.
JMarc
If you are already using a helper column and the combox box runs a macro after it changes, why not just adjust the macro and filter the source data?
Regards
I gotta say, it seems like you are giving 10 answers to 10 questions when your client REALLY wants to know is: "What is the last year "this" customer row had a non-zero Sales QTY?... You're missing the forest for the trees...
Change the helper column to:
=IFERROR(INDEX(tblSales[[#Headers],[Customer name]:[Sales 2012]],0,MATCH(9.99999999999999E+307,tblSales[[#This Row],[Customer name]:[Sales 2012]],1)),"NO SALES")
And yes, since I'm matching off of them for value, I would change the headers to straight "2002" instead of "Sales 2002" but you sort the table on the helper column and then and there you can answer all of your questions.
Hi thanks for this. Just can't figure out how you get the combo box to control the pivot table. Can you please advise?
Cheers
@Kevin.. You are welcome. To insert a combo box, go to Developer ribbon > Insert > form controls > combo box.
For more on various form controls and how to use them, please read this: http://chandoo.org/wp/2011/03/30/form-controls/
Thanks Chandoo. But I know how to insert a combobox, I was more referring to how does in control the year in the pivot table? Or is this obvious? I note that if I select the Selected Year from the PivotTable Field List it says "the field has no itens" whereas this would normally allow you to change the year??
Thanks again
worked it out thanks...
when =data!Q2 changes it changes the value in column N:N and then when you do a refreshall the pivottable vlaues get updated
Still not sure why PivotTable Field List says “the field has no itens"?? I created my own pivot table and could not repeat that.
Hi, I put the sales data in range(F5:P19) and added a column D with the title 'Last sales in year'. After that, in column D for each customer, the simple formula
=2000+MATCH(1000000,E5:P5)
will provide the last year in which that particular customer had any sales, which can than easily be managed by autofilter.
Somewhat longer but perhaps a bit more solid (with the column titles in row 4):
=RIGHT(INDEX($F$4:$P$19,1,MATCH(1000000,F5:P5)),4)
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