One of the most asked questions within the posts and Forums at Chandoo.org is “How Does Sumproduct work ?”.
Rahul recently asked for an example in Excels Sumproduct Formula post; Comment No. 55.
So today in Formula Forensics we will take a look at just that with a few worked examples.
Sumproduct
Excels help defines Sumproduct as:
So what are these arrays referring to:
An array in Excel can be :
A manual Array: {10;20;30}
A Range: A1:A3
A Named Range: MyRange1
Where MyRange1 is defined as a defined range in the Name Manager.
A Named Formula: MyRange2
Where MyRange2 is defined as a Formula returning a range in the Name Manager.
Lets look at each
You can follow along in the Example file on Sheet1
An Array
In C2 type: =SUMPRODUCT({10;20;30})
Excel will display 60, which is the Sum of the array elements =10+20+30
A Range
C7: =Sumproduct(C4:C6)
Excel displays 60, which is the Sum of the cells from the range C4:C6 =10+20+30
A Named Range
In the Name Manager or Name Box define a Named Range
MyRange1: =Sheet1!$C$4:$C$6
Then in C10 type:
C10: =Sumproduct(MyRange1)
Excel displays 60, which is the Sum of the range elements =10+20+30
A Named Formula
In the Name Manager define a Named Formula
MyRange2 =OFFSET(Sheet1!$C$3,1,0,3,1)
Then in C12 type:
C12: =Sumproduct(MyRange2)
Excel displays 60, which is the Sum of the range elements from cells C4:C6 =10+20+30
You may be asking why use Sumproduct when we can use a simple Sum to add up 3 numbers?
The answer is to show you what Sumproduct is doing, it is Adding up each Array element.
What about the “Product” part of Sumproduct ?
Remember back at the start where we saw the Definition of Sumproduct,
SUMPRODUCT(array1, [array2], [array3], …)
Only Array 1 is required, Array 2, Array 3 etc are optional, that’s what the square brackets [ ] mean.
Multiple Arrays
Goto Sheet 2 in the Example file:
We will look at a simple example using two arrays
The data consists of Sales data.
Often we want to know what the total sales are
We do this by adding a Sales column
Which multiplies the Qty and Price columns
And then Sum (Add) up this new column
Returning our Total Sales of 15,000
Now we can manually check the above as the numbers are simple eg: 100*20 = 2,000 etc
And we can sum up the Sales and see that we in fact had total sales of 15,000
Well this is exactly what Sumproduct is made to do:
In a Blank cell enter: =SUMPRODUCT(D4:D8,E4:E8)
Excel will return 15,000.
So what is Sumproduct doing?
Lets look inside and see what’s going on
In the Example File, Sheet2, H1 there is a copy of the data laid out as below
Note that our formula =SUMPRODUCT(D4:D8,E4:E8)
Has two Arrays
Array 1: D4:D8
Array 2: E4:E8
Note that each corresponding Array Element is multiplied together
100 x 20
20 x 200 etc
These are the products of the two Arrays
Finally the Products are Added together and the correct answer 15,000 is returned.
So Sumproduct is the Sum of the Products of the Arrays
Of course we can extend that to a large number of Arrays, columns in this case, if we wish.
Sumproduct with Logic
In the above two examples we saw that Sumproduct can Sum a single Array and can Sum the Product of two or more Arrays.
We can use that to our advantage and build logic into the arrays, allowing us to optionally include some array elements and leave out others.
How?
Sumproduct will always add up the product of all Arrays.
So by including an Array where the elements within the Array that we don’t want to Sum are Zero and the Elements within the array that we do want to Sum are 1 we can control what is included in the final Summation.
Goto our Example File on Sheet3
Lets say we only want to include the Sales from our Northern Region
One way to do this is to purely delete the other entries
But what if we could do that without altering our worksheet or there are thousands of rows of data?
This is where Sumproduct comes into its own.
What we need to do is add some logic to our equation, effectively doing:
Lets try it with Sumproduct
In Cell F12: type =SUMPRODUCT(D4:D8,E4:E8,{FALSE;TRUE;FALSE;FALSE;TRUE})
Excel displays a –
Excel doesn’t know what to do with the True/False and so converts them to 0
We can force excel to evaluate these as numbers by adding a simple “1*”
In F14: Type =SUMPRODUCT(D4:D8,E4:E8,1*{FALSE;TRUE;FALSE;FALSE;TRUE})
Excel now displays 5,000 the total sales from the North
To see what has happened in F16 type: 1*{FALSE;TRUE;FALSE;FALSE;TRUE}, but don’t press Enter press F9 instead.
Excel displays ={0;1;0;0;1}
The use of the 1* has converted each of the Array elements from a True/False to a 1,0 respectively.
So our 3 arrays are now:
Now adding an Array of 1*{FALSE;TRUE;FALSE;FALSE;TRUE} every time we wanted to add some numbers isn’t a practical solution.
Excel has the ability to work construct an Array on our behalf!
In E18: enter =SUMPRODUCT(D4:D8,E4:E8,1*(C4:C8=”North”))
Excel will display 5,000
So 1*(C4:C8=”North”) is exactly equal to our previous array 1*{FALSE;TRUE;FALSE;FALSE;TRUE}
1*(C4:C8=”North”) = 1*{FALSE;TRUE;FALSE;FALSE;TRUE}
At the heart of this is that Excel is evaluating each cell in the Range: C4:C8 against our required logic =”North” and setting up an Array for us internally.
Simplify
The power of Sumproduct is therefore in that we can now simplify and extend
In cell E20 type: North
In cell F20 type: =SUMPRODUCT(D4:D8,E4:E8,1*(C4:C8=E20))
Excel will display 5,000
This simple addition allows us to vary the Summation based on the value in E20
We don’t need to multiply our logic array by 1, we can actually use any number or another Array.
In cell F22 type: =SUMPRODUCT(D4:D8,(E4:E8)*(C4:C8=E20))
This works as (C4:C8=E20) is returning an Array of True/False which get converted to an array of 1/0’s when subject to any maths.
The Math in this case is the multiplication by the 2nd Array (E4:E8)*(C4:C8=E20)
In Cell F24 type: =SUMPRODUCT(Qty, Price *(Region=SalesRegion))
Excel will display 5,000
But notice that by using Named Ranges/Formula how simple the logic of the equation has now become.
Rahul’s Question (Multiple Criteria):
In Comment No. 55: Rahul asked, “Can you give an example work sheet of above example”
Sheet 4 in the Example File is the answer.
In Cell C23: type: =SUMPRODUCT(- -(A2:A21=”Luke Skywalker”),- -(B2:B21=”West”),C2:C21)
Excel will display 141, which is the sum of the Sales made by Luke Skywalker in the West Region.
However using what was learned above, this is better simplified to:
C26: =SUMPRODUCT((Name=SalesMan)*(Region=SalesRegion)*Sales)
The Double Unary
In the formula above Chandoo has used what is known as a Double Unary, which is 2 – signs next to each other (I have inserted a space above to make it more legible).
Two – signs are the same as saying
– -(A2:A21=”Luke Skywalker”) = -1 x -1 x (A2:A21=”Luke Skywalker”)
-1 x -1 is 1
Technically this is the most efficient way for Excel to perform any maths on the Array
– -(A2:A21=”Luke Skywalker”)
So that the Array of true/Falses made by (A2:A21=”Luke Skywalker”) is converted to an Array of 1/0’s for use in Sumproduct.
At the slight expense of speed but for improved readability and understandability by others I prefer the use of 1* instead of – – and you will mostly see that convention in my posts.
Chandoo: – –(A2:A21=”Luke Skywalker”)
Hui: 1*(A2:A21=”Luke Skywalker”)
In fact any maths performed on the array will convert its contents to an array of 1/0’s, so long as the maths doesn’t change the Arrays values
For a real good discussion on this topic have a look at the post The Venerable SUMPRODUCT at ExcelHero.com
Other Links to Sumproduct
http://chandoo.org/wp/2009/11/10/excel-sumproduct-formula/
http://chandoo.org/wp/2011/05/26/advanced-sumproduct-queries/
http://chandoo.org/wp/tag/sumproduct/
http://www.excelhero.com/blog/2010/01/the-venerable-sumproduct.html
DOWNLOAD
You can download a copy of the above file and follow along, Download Here.
OTHER POSTS IN THIS SERIES
You can learn more about how to pull Excel Formulas apart and what makes them tick in the following post:
FORMULA FORENSICS NEEDS YOUR HELP !
I am running out of ideas for Formula Forensics and so I need your help.
If you have a neat formula that you would like to share and explain, try putting pen to paper and draft up a Post as Luke did in Formula Forensics 003. or like above.
If you have a formula that you would like explained but don’t want to write a post also send it in to Chandoo or Hui.
XMAS BREAK
This will be the last Formula Forensics Post for 2011, but rest assured that we will be returning in early 2012.
I’d like to take the opportunity to thank Chandoo for allowing me the space and freedom to post pretty much what ever I’ve wanted at Chandoo.org. I hope you have enjoyed my contributions to the Chandoo.org community over the past year.
On behalf of Eva and myself I’d like to wish you all a very Merry Xmas and a Happy and Safe New Year ahead
Hui…
28 Responses to “Team To Do Lists – Project Tracking Tools using Excel [Part 2 of 6]”
[...] & tracking a project plan using Gantt Charts Team To Do Lists - Project Tracking Tools Part 3: Preparing a project time line [upcoming] Part 4: Time sheets and Resource management [...]
the templates are great (I bought the combo).
What I'm missing is a way to have the project gantt chart and reporting with the data per resource, in such a way that I can also show the occupation per resource on an extended gantt chart.
So with hours entered per person per project or sub-activity, to show a gantt chart of how many hours/days a person spent on which project (or plans to spend).
[...] from: Team To Do Lists - Project Tracking Tools using Excel [Part 2 of 6] 25 Jun 09 | [...]
Hi Chandoo,
Funny I have a post on the value of MS project lined up which I will post when the current monster project I'm working on finishes and I get some free time!
I'm not sure this would help with any of the projects I've worked on, closing down a to do list seems like more effort than it's worth, but it might be useful for some things. I guessing it doesn't, but does the time stamp not update when you recalculate the work book?
keep up the good work!
Ross
@Ross.. Thanks for sharing your ideas... I think to do lists are a great way to keep up with project activities and ensure accountability from individual team members, when they are implemented right.
"I guessing it doesn’t, but does the time stamp not update when you recalculate the work book?"
Your guess is right. When you change the calculation mode to "iterative", excel takes care of the nittygritties and retains older values in circular references in formulas.
[...] Project Management in Excel [New Series] - Gantt Charts | To Do Lists [...]
[...] & tracking a project plan using Gantt Charts Team To Do Lists - Project Tracking Tools Project Status Reporting - Create a Timeline to display milestones Part 4: Time sheets and Resource [...]
Hi Chandoo,
The template give me lot of convenience to monitor the thing to do. It simple. Thank You
[...] & tracking a project plan using Gantt Charts Team To Do Lists - Project Tracking Tools Project Status Reporting - Create a Timeline to display milestones Part 4: Time sheets and Resource [...]
[...] make sure you have read the first 4 parts of the series - Making gantt charts [project planning], team todo lists [project tracking], project time lines chart [reporting] and Timesheets and Resource Management using Excel. Also [...]
Chandoo,
I really do not see any befit to this function in Excel unless it was somehow tied into some other chart. That is say a scheduled activities % complete is based on the to-do list.
The only way this chart would be useful is if no one was assigned none dependent task that could be done by anyone. The cases were both of these conditions are true are so few and far between it really makes this chart worthless.
@Brian... Once you have a todo list up and running, it is easy to get metrics out of it. I didnt propose it as it might look a bit too micro-management-ish.
I am able to understand what you meant by "The only way this chart would be useful is if no one was assigned none dependent task that could be done by anyone. The cases were both of these conditions are true are so few and far between it really makes this chart worthless."
Can you explain?
"Chandoo"
What I mean is this. Lets say you have 10 task which are part of one activity/WBS that is in your schedule. One there are very few cases were many people would be assigned to complete this one scheduled activity with no direction being given who should what of the 10 task. It is poor management, and the task 90% of the time would not get done in a timely manner if say 4 people were responsible. Secondly, you are assuming all 10 task are independent of each other. You might need to do task 1 thru 3 before you can do task 4, and to do task 7 you might need to do 4 and 6. Thirdly, the time it would take to compile and then fill out the to-do-list even in limited applications is really not worth it.
I just see almost no applications why a team would need to inform others separate from the schedule that they have completed a task on a to-do list unless anyone of the 4 people could of completed that task.
My point is, there might be a few very limited applications for this type of list but this list would be worthless as a Project Management tool in every other case.
However, change this from a to-do-list to a document change log and it is perfect. Instead of to-do it is the documents name or summary of what changed in the document. The person is who edited the document, and the time stamp is when they checked it in. But I do not know why you would use excel when there is free software you can use commercially that is 10 times better that does document management.
I think using excel to do Project Management over a real Project Management application is a bad idea. Unless you are running a very small, simple project, the time and effort is a lot more to use excel compared to the cost of the Project Management software.
This comes back to my point, I love your site, however, just because you can do something in excel does not mean you should do it. To often the time it takes to use excel is wasted 10 times over from the cost of doing it in an application designed to for the specific application.
@Brian: The todo list mentioned here is meant to keep track of all the tasks for which detailed planning is not necessary but some sort of tracking is needed. These are not be confused with project activities (a la gantt chart).
I like your suggestion about using this as a document tracker. Pretty cool use.
Coming to your point about excel as a real project management tool, well, I have my views, but in a serious project environment, it would surely payoff to have a dedicated project management application.
[...] & tracking a project plan using Gantt Charts Team To Do Lists – Project Tracking Tools Project Status Reporting – Create a Timeline to display milestones Time sheets and Resource [...]
Chandoo,
Wonder how the timestamp column will maintain its previous data. Both Today() and Now() functions will update as and when the next timestamp happens.
[...] Preparing & tracking a project plan using Gantt Charts Part2: Team To Do Lists – Project Tracking Tools Part3: Project Status Reporting – Create a Timeline to display milestones Part4: Time sheets and [...]
I've combined this with the issue tracker since I like the automatic date stamp, but one thing I'm noticing is that I can't replicate the chart that goes along with the issue tracker because the cells that are referenced have the formula that inserts the time stamp instead of a the actual date value. All the dates of the last 30 days display 0 when they should have a value.
Is there a way around this?
I have edited the chart so that my team members can update the percentage completion of the assigned tasks. When the cell is updated, i would like the time stamp to update. How would I manipulate the formula to update whenever the drop-down list is changed?
[...] … ??? To Do List [...]
Excel is great however sometimes you need to get a better idea of what tasks each person on your team is working on at any given time. We've developed a web app that can do just that! Each person has a list of tasks, listed in the order they have to complete them.
HII,
I want to expand the database through excel where i am working on 11 cities as of now and i want to expand it upto 50 cities and hence forth the data related to it will also expand so i want to make it precise where i can get updates also that this work is required to be done at that particular day or date
Thanks for making all of this information available for free. I am currently using excel to track everything for the first time. I later plan to output our information here with a more visual presentation. Wish me luck!
Can some one point me out to some additional direction on the "Who Finished it?" column? Something more 'basic' for a newbie excel guy? lol I got everything else working on this tutorial but that column. I can't seem to recreate it and I know a lot of it is due to lack of knowledge with VB code. I'd like to recreate this column very much 🙁
Dear Chandoo,
Thanks for the team to do list, kindly let me know how to set the column who " finished it " from another work sheet
Hi Chandoo,
Unable to download it - can you please check the link and confirm.
Great inhisgt! That's the answer we've been looking for.
Hi Team,
I know u all are the best programmers in the world!!! that's I am here to rectify my issues. here is my question please ans me as soon as possible before 8-3-2017 its really urgent.
I have a project named the production tracker.
1) I require the user form which shows the names of the Associates which are linked to the different tracks. when the user is selected the particular track related details and dropdowns should appear.
2) I need to track the associate needs how much of the time to complete the particular task. with start stop and pause and resume timer.
3) It should display the daily count of the production and save the data to the another Excel file.
this production tracker should save all the data no matter how many people logs in into it.
Please help me for this it will be very appreciated.
you can directly email me on my mail ID: tusharkch694@gmail.com