Here is a little experiment to freak out excel.
Go to cell C3 and write =C3 and press Enter. Excel would throw up nasty message saying, “Microsoft did not know what to do. We have a sent a support engineer to your home, but he is stuck at the round-about near your house.”
Well, not really. But what you did when you wrote the formula =C3 in cell C3 was, you created a circular reference.
What is a Circular Reference & why use them?
A circular reference is created when you refer to same cell either directly or indirectly.
We use circular references when we need circular references.
Excel Circular Reference Example:
For eg. (borrowed from John Walkenbach’s Excel 2010 Bible), lets say you run a fictitious company named Sky is the Ltd.
And you have a strange policy of donation 10% of your profits after tax to charity.
But, in your country, charity donations are tax exempt (they are expenses).
So charity = 10% * after tax profits
after tax profits = (revenues - expenses - charity)*(1-tax rate)
By definition, charity refers to after tax profits, which refers to charity, thus creating a circular reference.
Now, how would you find out how much to donate to charity?
Simple, we write formulas with circular references, like this:
But wait, just when you press enter after writing the formulas, Excel would scream bloody and curse your entire family for having a circular reference in your worksheet.
Enabling Iterative Calculation Mode
You must enable what they call iterative calculation mode before the formulas work. For this we must go to Excel Options.
In latest versions of Excel,
- Click on Office button
- Go to Excel Options, this is analogous to opening the bonnet of your car, but just a bit more confusing.
- Locate the “Formulas” on the left, click on it
- Now, check the “Enable iterative calculation”. This way you are telling Excel to evaluate references iteratively, up to 100 times (default).
- Click ok, close the bonnet. That is all.
In per-historic versions of Excel,
- Go to Menu > Tools > Options > Calculation Tab
- Check Iterative Calculation box. (see image)
Once you do this, your formulas will work nicely and you will find that the required charity donation to be made.
How to avoid Circular References?
As you can understand circular references are a pain in cell. You may want to get rid of them altogether. Thankfully, with careful inspection and a mug of coffee, you can reduce most circular references to simple formulas. For eg, in the above case, we can calculate charity amount directly by using the following equations.
But, keep in mind that, in few cases, circular references may be required. For eg. if you want to add timestamps to your workbook.
How to locate Circular References?
Do you know that you can find all the circular references in a workbook?
Whenever you see circular reference warning message, just go to formula ribbon and click on error checking options. You can see all the circular references there.
Note: In Excel 2003, you can see the same from circular reference toolbar (Menu > View > Tool-bars > Circular Reference)
Examples & More Resources on Circular References:
- Add timestamps to your workbook
- Team Todo List template in Excel
- Circular References & Other Repetitive Calculation Features in Excel
- Solve Circular References instead of using them
Do you do circular references?
I try to avoid circular references whenever possible. But in some rare cases, I think a circular reference gives elegant, shorter solution than a non-circular variation of it.
What about you? Do you use circular references often? What are the reasons / uses of them according to you? Please share your experience, tips thru comments.
PS: Here is a very useful link on circular references.
PPS: Monalisa pic source is here.
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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