Looking up when the data won’t co-operate (case study)

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Occasionally we deal with data that is so uncooperative that we might as well give up and go back to calculators & ledger books.

Recently I found myself in such a situation and learned something new.

Introducing … data that won’t play nice

Drum roll please. Here is a data-set that I got from somewhere.

2D Lookup problem - Example dataset

The problem – build a lookup formula

And the problem. Oh, simple. Write a lookup formula to find how many customer walk-ins we have on any given day.

But how?

After wrestling with a few variations of VLOOKUP, INDEX, MATCH, OFFSET… I found the right formula for this occasion.

SUMIFS Formula

That’s right, the good old (well, its just 7 years old, born in 2007 Excel) is the one that works in this situation.

Assuming our data is in the range:

  • B4:H15
  • Even rows (4,6,8…14) containing date
  • Odd rows (5,7,9…) containing customer walk-ins
  • And lookup date is in L5

We can use this SUMIFS formula:

=SUMIFS(B5:H15,B4:H14,L5)

to find out how many customers walked in to the store on the lookup date.

How does this formula work?

See this illustration.

2D Lookup formula with SUMIFS - how it works

 

Since SUMIFS (and SUMIF too) formula works in 2D, our formula works elegantly.

Any caveats?

There are a couple of problems with this formula.

  1. It works for looking up numbers only
  2. It doesn’t work if any of the numbers are same as dates we are looking up. For example 15th October 2014 is 41927, so we have a data point that is also 41927, then our SUMIFS result would be wrong.

A better formula?

If you want a formula that works with any type of data, then of course we can come up with one.

That is your home work.

Go ahead and figure it out and share your magic potions in the comments.

Here is a clue: If we cant go somewhere directly, we can go indirectly, if we know the address.

Download Example Workbook

Click here to download the example workbook. Examine the formula in cell L6 to understand how this works.

How do you deal with such data?

Badly shaped data is everywhere. Not a week goes by when I don’t come across poorly structured data. Thanks to Excel, I can alter the shape of almost any data. My favorite techniques are – text import, power query, formulas, pivot tables, remove duplicates & go to special.

What about you? How do you deal with poorly structured data? What tools do you deploy to alter the fitness levels of your data? Please share your thoughts and tips in comments.

Don’t forget about the formula challenge.

Excel not co-operating? Its time you tamed it

Data that is messy, bosses with high expectations, coffee machines that don’t work are everywhere. Fortunately Excel can fix 2 of those 3 problems. (Sorry folks, there is no fixCoffeeMachine() macro, yet.)

Learn a few Excel tricks & concepts and you could be on your way to taming messy data & demanding bosses. Start with these:

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19 Responses to “How to Distribute Players Between Teams – Evenly”

  1. Roshan Thayyil says:

    An excellent solution, especially for large data sets.

    Another solution without using solver would be to assign the player with the highest score to Team 1, the 2nd to team 2, 3rd to team 3, 4th to team 3, 5th to team 2, 6th to team 1, 7th to team 1 and it continues. This method would end up with a Std Dev of 0.001247219. This works best with a distribution with lower Std Dev for the dataset.

    Full Disclosure: this is not my idea, remember reading something a few years ago. Think it may have been Ozgrid

    • Roshan Thayyil says:

      thinking back I now remember why I read about it. About 10 years back I had to distribute around 300 team members into 25-30 odd teams. Used this method based on their performance scores. I used the method I described to do this and the distribution was pretty fair.

      Solver would have saved me a ton of time though 🙂

  2. I think the issue with you first Solver approach was that you took the absolute value of the sum of team deviations (which should always be zero except for rounding) instead of the sum of the absolute values (which is a reasonable measure of how unbalanced the teams are).

  3. Here's another simple algorithm you could use: you start from the top (with players sorted from high to low), and at each step allocate the next player to whichever team has the smallest total so far. You can implement it dynamically with some formulas so it will update automatically when the data changes.

    If the scores were more widely distributed (so that this might end up with not all teams the same size), you could add a constraint to only pick among the teams which currently have fewest players at each step, or just stop adding to any team when it hits its quota.

    When I tried it on the sample, I got the three teams below, with a STDEV of 0.000942809 (i.e. about half of what Solver got to).

    Team 1: John, Hugo, Tom, Josh, Eric, Zane, Charles, Andrew
    Team 2: Barry, Michael, Kenny, Joe, Xavier, Patrick, Oliver, William
    Team 3: Henry, Steven, Ben, Frank, Kyle, Edward, Cameron, Lachlan

    Thanks for sharing!

    • Ishaan says:

      Hi,
      I was looking at all the solutions and this is closest to what I intended to do. I am dividing a bunch of players into 3 soccer teams. Players availability is also a factor while deciding the teams.
      So the steps the excel needs to do is as follows:
      1) In availability column if "yes" go to next
      2) Equally divide 'Goalkeepers', 'Strikers', 'Defenders' basis their quality
      So the end result gives each 3 teams a balance of players playing at different positions.
      Can this be done on Google spreadsheet with only availability as an input from the user and rest calculates by itself.
      Sorry for asking such a pointed question, but I have been struggling to find a solution for it for sometime now!

      • Robin says:

        Hi Ishaan,

        I am working on a similar problem at the moment, so I am wondering if you ever found a solution and if you are willing to share what you did.

  4. Konrad says:

    Hi everyone, this is a variation of the famous Knapsack Problem https://en.wikipedia.org/wiki/Knapsack_problem.

    I had to use a VBA implementation recently as part of a problem, where we ar trying to allocate teams of an organization into different locations (we are a large company with many different team). The goal was to optimally allocate teams to individual buildings without putting too many teams into one building and not splitting teams apart.
    As we had around 400 teams of different sizes, solver couldn't handle it anymore. Luckily there is a Knapsack algorithm implementation in VBA readily available on the internet :).

    I also went with a heuristic approach first!

  5. Joe Egan says:

    An interesting mathematical solution but what if Eric and Xavier can't stand each other or Patrick is best friends with Steven - the real life problems that effect "even" teams.

    • Hui... says:

      @Joe

      You can add more criteria like
      If Eric and Xavier can't stand each other
      =OR(AND(E15=1,E16=1),AND(F15=1,F16=1),AND(G15=1,G16=1))
      It must be False

      If Patrick is best friends with Steven
      =OR(AND(E5=1,E17=1),AND(F5=1,F17=1),AND(G5=1,G17=1))
      It must be True

      Note that the 2 formulas above are exactly the same
      except for the ranges
      One must be True = Friends
      One must be False = Not Friends

  6. Gustavo Sousa says:

    Nice post Hui!

    I download your workbook and just try to change in options the Precision Restriction from 10E-6 to 10-8 and the Convergence from 10E-4 to 10E-10. The process take almost the same time, but the results was great.

    The standard deviation I got was 0,000471.

    Team 1: John, Tom, Kenny, Frank, Eric, Xavier, Edward, Zane
    Team 2: Steven, Hugo, Ben, Joe, Josh, Oliver, Cameron, William
    Team 3: Barry, Henry, Michael, Kyle, Patrick, Charles, Andrew, Lachlan

  7. Charlie says:

    Great application of Solver! Thanks for the link!

  8. Chuck says:

    Great explanation. Well done... However, I tried with 6 teams of 4 players and solver never did finish.

  9. Akbar says:

    How about vba code for the same data set.
    I have 3 column A B C wherein A has text and B has number Wherein C is blank. And in C1 been the header C2 where I want the name to come evenly distributed the number which is in Column B.
    My Lastcolumn is 1000.

  10. HRMFT says:

    Sorry if I'm being slow here, but how is 'Team Score' calculated? I've gone through the explanation several times but it seems to just appear.

    • Hui... says:

      @Hrmft

      This process uses the Solver Excel addin

      Solver is effectively taking the model and trying different solutions until it gets a solution that meets all the criteria
      Then solver puts the solution into the cell and moves to the next cell

      So yes it appears to "just appear"

  11. Caroline says:

    Hi ! Thank you so much ! Works great 🙂

  12. Jim Cruse says:

    I cannot get the fourth Equation to work in my excel spreadsheet
    You have =($E$2:$G$25=0)+($E$2:$G$25=1)=1 as a SUMIF solution, I have, =($F$2:$H$13=0)+($F$2:$H$13=1)=1 as my solution but it does not work. The only thing I changed is the ranges. Any suggestions?
    Thank you.
    Jim

  13. Jim Cruse says:

    I cannot get the fourth Equation of TURE or FALSE statements to work in my excel spreadsheet You have =($E$2:$G$25=0)+($E$2:$G$25=1)=1 as a SUMIF solution, I have, =($F$2:$H$13=0)+($F$2:$H$13=1)=1 as my solution but it does not work. The only thing I changed is the ranges. Any suggestions?
    Sorry I left some of it out in the previous question,
    Thank you. Jim

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