Last Friday, we had a fun little Excel challenge – Calculate Maximum Change. More than 170 people commented and shared their solutions to this problem.
And the best part?
The best part is the variety of solutions & thinking displayed by our community. So if you are one of those 170, puff your chest & pat yourself on the back. Go ahead, I will wait.
Today, lets take a look at some of these awesome formulas and understand how they work. Read on and watch the video you below to gain few awesomeness pounds.
First, lets understand the problem
Here is a look at the problem:
We need more information to answer this question.
- Are we talking about positive change, negative change or absolute change?
- Are we talking about % change or value change?
In the original problem, even though I did not mention it, most people assumed that we want absolute change of value (ie the answer is 40, for Product 2).
But in real life, you may want to understand the problem a little more before writing any formulas.
Note: The data is in C3:C8 for last month and D3:D8 for this month.
Solution #1: Using MAX array formula
This is the solution most people got.
The array formula:
=MAX(C3:C8-D3:D8)
press CTRL+Shift+Enter after typing.
How it works?
C3:C8-D3:D8 portion: This gives the result {-20;40;15;21;0;-25} in array form.MAX(…) portion: This simply calculates the maximum value of above array and returns 40 as answer.
Why press CTRL+Shift+Enter (CSE)?
We need to press CTRL+Shift+Enter because MAX() is not capable of handling arrays. If you write MAX({-20;40;15;21;0;-25}) you would get 40, but the same array when calculated by doing math on ranges will not work. To force MAX to treat arrays, we need to press CTRL+Shift+Enter.
Solution #2: Using MAX+ABS array formula
Quite a few people figured out that the formula needs to work even when the change is negative. And that is where this new solution comes handy.
The array formula:
=MAX(ABS(C3:C8-D3:D8))
press CTRL+Shift+Enter after typing.
How it works?
ABS() portion: converts the change values {-20;40;15;21;0;-25} to positive {20;40;15;21;0;25}
Rest of the formula is same as solution #1.
Solution #3: Using INDEX to avoid Ctrl+Shift+Enter
The thing with Ctrl+Shift+Enter is that you have to remember it. If you accidentally press Enter instead of CSE, the formula stops working. One way to avoid this is to route the calculation thru an Excel function that can natively process arrays. This is where INDEX (or SUMPRODUCT etc.) come handy.
The formula:
=MAX(INDEX(C3:C8-D3:D8,0))
or
=MAX(INDEX(ABS(C3:C8-D3:D8),0))
How it works?
Same as Solution #1, except for this formula you do not have to press Ctrl+Shift+Enter. The INDEX will automatically calculate the array and send numbers to MAX. Then MAX feels mighty comfortable dealing with those numbers and spits out the answer as 40.
Learn more:
Solution #4: Using AGGREGATE
AGGREGATE() is a new function introduced in Excel 2010. This too, like INDEX & SUMPRODUCT can process arrays natively (provided you are using one of the aggregates like LARGE). Kyle, one of our commenters shared 2 brilliant solutions that involve AGGREGATE.
The formula:
=AGGREGATE(14,4,(C3:C8)-(D3:D8),1)
How it works?
14, 4 portion: This tells AGGREGATE that you want to calculate LARGE value (14) and you want to consider all cells (4). To understand more about AGGREGATE see the links below.
(C3:C8)-(D3:D8) portion: As seen above, this just gives an array – {-20;40;15;21;0;-25}
1 portion: This tells AGGREGATE that you want 1st largest number.
Learn more:
Solution #5: Using MMULT and AGGREGATE
Now this is what I call a scary formula. It can potentially waste your entire afternoon when you try to understand it first time. But once you get it, you feel awesome. This too is posted by Kyle.
The formula:
=AGGREGATE(14,4,MMULT(C3:D8,{1;-1}),1)
How it works?
Watch the video. Explaining how this works in text is difficult.
Learn more:
I am still trying to understand MMULT(). It can be as complex and deep as string theory (or recipe of making bread at home). Go thru below links to learn more about it. Make sure you put on your helmet, cause it will blow your mind.
More ways to get maximum change + Bonus problem
Watch below video to understand how to solve the maximum change problem and another related problem.
Click here to watch if you can’t see the video above
Download Answer workbook
Click here to download answer workbook and examine the formulas to learn more.
What did you learn from this formula challenge?
I learned how to use AGGREGATE, Array SUMIFS and got a better handle on MMULT.
What about you? What did you learn thru this challenge. Please comment and let us all know.
7 Responses to “Project Dashboard + Tweetboard = pure awesomeness!!!”
I would like to see actual hash-tagged DM tweets go out to the specific information consumers. That would be an interesting way to communicate the key daily data to interested parties.
A Twitter-like secure application like Yammer might be a good fit with this.
For example, how about daily tweets to selected user groups (secure) that would display sales, bookings, cash receipts, cash disbursed and a second version that would show the same info for MTD, QTD or YTD figures.
@Dan, it would be great. I did not taught about implementing it on this dashboard because twitter is blocked to the whole intranet here. However, there's a discussion here about how can we send these tweets to blackberries (probably through e-mail) automatically. (I'd like to see this implemented on a jabber restricted network as well, but here it'll probably not happen)
The wrap-up versions you mentioned doesn't apply to my particular scenario, but on a sales tweetboard it would be a great tool indeed - choosing who will receive which message according to hashtags. I'll think on something, thanks for the advice. 🙂
(Ah, btw, I'm Fernando... 🙂 )
@Dan: That is a fun idea. Instead of tightly integrating twitter functionality with a dashboard, i think it would be cool if we have a "tweet this" button that users can click after selecting a range of cells. We can easily show a dialog with the concatenated output of the selected cells and ask user to edit the text and eventually "send to twitter".
For eg. you can select the annual sales figure cell and click on "tweet this" button upon which a dialog will show the value. Then you can pre-pend it something like "DM @boss look at our sales this year: "
@Aires.. thanks once again.
Wow it looks really good. Not sure though how much the tweet facility would help in real world project management, but certainly having a dashboard on a project should be a key deliverable when learning how to manage a project
The other use of this is during the software development life cycle especially when you have parallel streams of development and testing going on. Using a dashboard is a quick way for everyone on the team to see where the project is at and how it all fits together.
Regards
Susan de Sousa
Site Editor http://www.my-project-management-expert.com
Hi Chandoo,
I purchased the project management toolkit but the dashboard shown above with the imbedded scroll bars. Is it included in the project pack??
Thanks
Sue
The gantt chart section of this dashboard is similar to one I have recently created: http://xlcalibre.com/hr-dashboard-gantt-chart-traffic-light-reportIt has a similar approach with scroll bars, but has a couple of additional features. I've tried to incorporate a traffic light report element, and also allow the timescale to adjusted so that can view it by days, weeks or months.I really like the other tables that you've incorporated, I may well try to replicate them to improve my version!
I am a monitoring and evaluation consultant in international development, and one of the services I offer is to help non-profits and foundations develop performance dashboards. I often advise them to develop dashboards for ongoing programs, rather than for one-time or pilot projects, because of the time involved. I am trying to find out from a few people how long it takes you to develop a project management dashboard, and to what extent the indicators vary from one project to the next.