Finding the closest school [formula vs. pivot table approach]

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First a quick personal update: There has been a magnitude 7.8 earth quake in NZ on 14th November 2016 early morning. It is centered in Kaikoura, which is about 250 km away from Wellington. We did feel several shakes and after shocks. It has been an interesting and often scary experience. But my family is safe. I feel very sad for the all the damage and the loss for families in NZ. If you suffered from this quake, My prayers and thoughts are with you.

Yesterday, a friend asked me an interesting question. He has school distance data, like below. He wants to know which is the closest school for each school.

school-data

There are a few ways to answer this question. Let’s examine two approaches – formulas & pivot tables and see the merits of both.

Formulas to find closest school

All the distance data is in a table named dist. 

Assuming you have school names & types in cells H5, I5, we want to find out the closest school of any type and same type in adjacent columns, as shown  below.

closest-school-calc

Let’s take a look at the formulas first. All of these are array formulas. So press CTRL+Shift+Enter after typing.

  • J5: Closest School Distance (Any type): =MIN(IF(dist[From]=H5,dist[Distance]))
  • K5: Closest School Name (Any type): =INDEX(dist[To],MATCH(H5&J5,dist[From]&dist[Distance],0))
  • L5: Closest School Distance (Same type): =MIN(IF(dist[From]=H5,IF(dist[To Type]=I5,dist[Distance])))
  • M5: Closest School Name (Same type): =INDEX(dist[To],MATCH(H5&L5,dist[From]&dist[Distance],0))

How do these formulas work?

Let’s examine them one at a time.

Closest School Distance (Any type)

Formula: =MIN(IF(dist[From]=H5,dist[Distance]))

How it works: 

  • We check if From school is same as the one in H5 and get the corresponding distances only.
  • This will return a bunch of distances and FALSE values. Distances will be listed only for the schools that match H5, for all others, the IF() gives FALSE.
  • We then pass this list to MIN formula to find the minimum distance.

As we are using arrays inside IF formula, we must press Ctrl+Shift+Enter to get correct results.

Related: Learn more about MAXIF & MINIF formulas.

Closest School Distance (Same type)

Formula: =MIN(IF(dist[From]=H5,IF(dist[To Type]=I5,dist[Distance])))

How it works: 

  • We check if From school is same as the one in H5 and if the [To Type] is same as I5 and get the corresponding distances only.
  • This will return a bunch of distances and FALSE values. Distances will be listed only for the schools that match H5 and of type I5, for all others, the IF() gives FALSE.
  • We then pass this list to MIN formula to find the minimum distance.

Finding the corresponding school name:

Once we know the minimum school distance, we just use array MATCH to find corresponding school number and get the name of the school with an INDEX().

=INDEX(dist[To],MATCH(H5&J5,dist[From]&dist[Distance],0))

As we are concatenating two lists in the MATCH formula, we need to press Ctrl+Shift+Enter to get correct results.

We use same logic to fetch school name for the distance in column L too.

Related: Learn about multi-condition lookups

Formula approach – comments

While the formula approach gives answers we want, it is very tricky to write these formulas. The MIN(IF(…)) structure is not easy to master.

As the formulas check entire data, they can be very slow on large sets.

Pivot table to find closest school

First create a pivot table from the dist table with below settings:

  • Add From and From type to row labels area
  • Add To and To type to column labels area
  • Add distance to values area, summarize it by SUM
  • Remove sub totals & grand totals
  • Set up pivot in tabular layout

We get this.

school-distances-pivot

At this stage, finding closest school gets easy. We simply use SMALL formula on each pivot table row to find 2nd smallest value (because smallest value is 0 and we should ignore it.) to get the distance. Finding school name is a simple matter of using INDEX + MATCH.

Of course, finding the distance for closest school of same type still requires using array version of SMALL with SMALL(IF(…)) structure. But this formula would be significantly faster as we don’t process all the 10000 rows of data.

Comments on Pivot Table approach

Pivot table approach simplifies the problem and helps us answer the questions faster. You can also apply conditional formatting on top of Pivot Table to instantly highlight closest school(s).

Download example workbook

Click here to download the closest school example workbook. Play with the formulas & pivot table to learn more. Examine the conditional formatting rules for some cool techniques.

How would you find the closest school?

By asking your neighbors, of course. Jokes aside, how would you find the closest school for a given school? Would you use formulas or pivot tables or some other approach? Please share your thoughts in the comments.

Need to learn, here is your closest school

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15 Responses to “Highlight Employees by Performance Rating – Conditional Formatting Challenge”

  1. Stephen says:

    While this might solve the question Shelly asked, there is another option that might be more useful - a pivot table could make a list of people who fall into the various categories, so, if you needed to simply see who got in the top bracket to give them a bonus, you would have that list

    Simply sorting by the rankings would work too, but you would knock them out of alphabetical order. 

  2. Darin Myers says:

    Normal
    0

    false
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    EN-US
    X-NONE
    X-NONE

    /* Style Definitions */
    table.MsoNormalTable
    {mso-style-name:"Table Normal";
    mso-tstyle-rowband-size:0;
    mso-tstyle-colband-size:0;
    mso-style-noshow:yes;
    mso-style-priority:99;
    mso-style-parent:"";
    mso-padding-alt:0in 5.4pt 0in 5.4pt;
    mso-para-margin-top:0in;
    mso-para-margin-right:0in;
    mso-para-margin-bottom:10.0pt;
    mso-para-margin-left:0in;
    line-height:115%;
    mso-pagination:widow-orphan;
    font-size:11.0pt;
    font-family:"Calibri","sans-serif";
    mso-ascii-font-family:Calibri;
    mso-ascii-theme-font:minor-latin;
    mso-hansi-font-family:Calibri;
    mso-hansi-theme-font:minor-latin;
    mso-bidi-font-family:"Times New Roman";
    mso-bidi-theme-font:minor-bidi;}

     
    The solution I chose makes use of the percentile formula.
     
    The percentile formula returns the value representing the K-th percentile of a range of values. The range of values is the first criteria, and K is the second criteria in the formula.

    I applied Conditional Formatting according to the formulas in the order below:

    5%    =$C6>=PERCENTILE($C$6:$C$33,0.95)   Dark Blue
    15%  =$C6>=PERCENTILE($C$6:$C$33,0.85)   Light Blue
    65%  =$C6>=PERCENTILE($C$6:$C$33,0.1)     Green
    10%  =$C6>=PERCENTILE($C$6:$C$33,0.05)   Light Red
    5%    =$C6<PERCENTILE($C$6:$C$33,0.05)     Dark Red
     
    The issue I noted with this approach is that Zambi was not highlighted in my solution as it is in the solution provided. Unless I am mistaken, and I very well may be, the 10th percentile for this data set is at 2.21, so Zambi would fall above the 10th percentile with a PR of 2.3.
     
    The first step to this was figuring out the 'buckets'; what scores should fall into each range. In attempting to match the formatting of the spreadsheet, I determined the buckets below.
     
    5% = 95% to 100%
    10% = 90% up to but not including 95%
    65% = 10% up to but not including 90%
    10% = 5% up to but not including 10%
    5% = under 5%
     
    After that, it is a relatively simple matter to plug the necessary values into the conditional formatting formulas as shown above.

    One final consideration is that while the buckets above match the color banding on the spreadsheet, I believe that the original request suggests a different color banding with 6 buckets shown below.
     
    Top 5%    = 95 to 100%    Dark blue
    Top 10%  = 85 up to but not including 95%    Light blue
    Top 65%  = 35 up to but not including 85%    Green

    Bottom 10% = 10% down to but not including 5%   Light Red
    Bottom 5%   = 5% or under    Dark Red
     
    This leaves one final bucket of 10 to 35% (exclusive of both values) that is not highlighted and so would remain white.
     
    Thank you Chandoo and Shelly for an interesting and useful exercise. This is certainly a valuable technique to have in my reporting bag of tricks.
     

  3. PSG says:

    Use of PERCENTILE is a smarter way of doing it.  Below is my solution.
     
    First 5 % = Apply conditional formatting (Dark Blue) as highlight ">=" =PERCENTILE(C:C,0.95)

    Next 15% = Apply conditional formatting (Lighter Blue) as highlight between =PERCENTILE(C:C,0.95)-0.01 and  =PERCENTILE(C:C,0.8)

    Next 65% = Apply conditional formatting as highlight (Olive Green) between =PERCENTILE(C:C,0.8)-0.01 and  =PERCENTILE(C:C,0.15)

    Next 10% = Apply conditional formatting as highlight (Lighter Red) between =PERCENTILE(C:C,0.15)-0.01 and  =PERCENTILE(C:C,0.05)

    Bottom 5% = Apply conditional formatting (Red) as less than =PERCENTILE(C:C,0.05)

    • Shailesh says:

      I agree, this is a challenge faced by HR managers every year and use of percentile formulae is the most popular solution which permits further processing like making bell curve, applying increments based on segmentation etc.

  4. Mayank Bhatia says:

    Hi Chandoo,

    I came at the same solution as yours (not looking at yours first) but I have hard coded the conditions in the conditional formatting. For example:

    =AND($C6>=$D$10,$C6<$D$9)

    I have done the same thing 5 times for each condition.   This makes the formatting independent of the order of specification. I think it will work better across versions of excel.

    To copy the same thing in all sheets, Shelly can copy these formatted cells with format painter and apply it to the relevant cells in next sheet and so on! I know 700 sheets will be difficult but I dont know of any other way to apply conditional formating rules to the whole sheet.

      

  5. Sameer Srivastava says:

    First i have used percentile formula in the next column of "percentile Threshold" where E5, E6.. is input to colour code.
    The idea behind doing this is to replicate the formula for any range and any threshold

    =PERCENTILE($C$3:$C$30,1-E5)

    =PERCENTILE($C$3:$C$30,1-E6)

    =PERCENTILE($C$3:$C$30,1-E7)

    =PERCENTILE($C$3:$C$30,1-E8)

    =PERCENTILE($C$3:$C$30,1-E9)

    Now i have given logic to different employee by applying "if Formula"

    =+IF(J3>=$G$5,1,IF(J3>=$G$6,2,IF(J3>=$G$7,3,IF(J3>=$G$8,4,5))))

    where 'J"  referes to PR and "G" refers to percentile derived from above mentioned formula.
    once again it is replicable (just change reference points)

    Now comes the major part of Conditional Formatting, i have used "use a formula to determine which cells to be formatted" 
    Formula =$j=5, format "required colour" Applies to "$I$3:$J$30" 
    plus put tick on stop if true

    This solves the query, important point that this is repeatable and can be done for n number of departments

    Thanks !

  6. Deepa says:

    I had done some reading on it and in Excel 2010 a new function has been introduced, percentile.exc. Attaching a video which also talks why the old percentile function shouldn't be used as it acts erroneous at times. Might be worth a watch Chandoo,
    http://www.itechtalk.com/thread10579.html

    • Hui... says:

      @Deepa

      Quit correct.

      Where ever you use statistical spreadsheet functions and are using excel 2010 you should use the new versions of the functions as MS did a lot of work to speed up and fix errors in the old functions.

      Warning: If you use the new Excel 2010 statistical functions in Named Formulas most of them will crash excel so do keep that in mind.

  7. Kishore says:

    Hello Chandoo,
    When i first read the challenge file, i thought, the color that need to be applied for a given rule, also need to be picked dynamically as given in rule set. But in the solution file, i found that color is hard Coded. So in case, someone has same data, but wants different colors, he/she needs to goto manage rules and change colors.
    Let me know if my understanding is correct, and if yes, can we also make the color to be applied dynamic?
     
    Thanks
    Kishore

  8. Roger L Moreno says:

    HI I ALSO USED THE PERCENTILE FUNCTION. HOWEVER, I WENT A STEP FURTHER AND USING THE SMALL() FUNCTION I SORTED THE DATA BY PERCENTILE SO THE COLOSCHEME WOULD BE GROUPED BASED ON THE VALUE. THIS WAY IT IS BETTER AND EASIER TO VIEW.

  9. [...] recently posted a challenge to help a reader with a [...]

    • Balraj says:

      Hi, i have got doubt regarding to the percentages that has been put in chandoo's spreadsheet, i cant understadn how he put directly. can some one please explain how chandoo put the percetages straight way that i stated below..

      5%

      15%

      60%

      10%

      5%

  10. I have stumbled on this post as the solution has been already given so I have taken the liberty to record a video where I show the implementation of it as well as adding a filtering feature which I hope can prove to be useful.

    Thank you

    http://www.xlninja.com/2012/06/28/how-to-use-excel-to-highlight-employee-performance-rating/  

  11. [...] scriu nici macar un cuvant din urmatorul articol. Astazi mi-am citit mailul si hopa challenge de la Chandoo. Cum puteam sa refuz asa ceva si m-am apucat de citit, iar dupa 5 min i-am spus sotului ca pe asta [...]

  12. Yves S says:

    Question for Chandoo:
    I came to your site late but am totally loving these challenges 🙂

    I guess it all boils down to how the bins are set up.
    I agree with the PERCENTILE.INC function.

    pls help me understand where I am wrong.

    I have determined following the bins:

    bottom 5% <=2.00 (F6:F33 <=PERCENTILE(range,.05))
    lower 15% (5+10) <= 2.40 (F6:F33 <=PERCENTILE(range,.15))
    lower 80% (5+10+65) <=3.46 (F6:F33 <=PERCENTILE(range,.80))
    lower 95% (5+10+65+15) <=4.00 (F6:F33 =PERCENTILE(range,.95))
    top 5% <=4.20 (F6:F33 <=PERCENTILE(range,1.00))

    I find that only Tom is highest scorer and unique top 5% achiever.

    I notice that Chandoo has included Christy and Daniel in top 5% achievers. How can there be 3 people in top 5% out of a population of 28 (5% of 28 = 1.4, i.e. only one person can achieve that status)?

    I tried different ways but cannot get to that distribution.

    Rest of the work is simply organizing the conditional formatting rules with Stop If True box checked.

    Thanks for your insights

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