“Start with a joke.” My boss used to say when I am nervous about an upcoming presentation. Although, I am not nervous to post this article, I think a joke will always help.
So here it goes:
[originally posted on 5th May 2008]
Now to more serious matters.
VLOOKUP (and other lookup formulas) are very powerful and quite practical. They can fetch you the information you are looking for from a heap of data.
Now that we have seen the power of VLOOKUP thru several posts this week, I want to test your understanding of these formulas by presenting 3 challenges.
Download the excel workbook with these challenges
Click here to download excel workbook with all the data for these challenges.
Challenge # 1: Price After Discount
We come across this problem quite often. You have a list of discount codes and applicable quantity thresholds. For eg. you may sell an item at $50, but if I buy more than 1 item, you will give a 10% discount. The discount goes up as I purchase more quantity.
Now, given a list of item quantities, how do you calculate the amount payable using lookup formulas? That is our first challenge.
Challenge # 2: Price after accumulated quantity discount
This is essentially same as above formula, but the discounts apply on accumulated quantities bought so far. For eg. I will get first item for 0% discount, 2nd and 3rd items for 10% discount, 4th item for 15% discount … 26th item for 50% discount etc.
Now, given a list of customer names and quantities they bought (in the same order), how do you calculate the amount payable for each transaction?
Challenge # 3: Closest price based on the quantity purchased
This is an interesting challenge. The price after discount is determined based on the quantity bought. For eg. the discount thresholds are 1, 3, 5, 10, 25 etc. Now, given a quantity of items bought, we determine the price by finding the closest threshold to it. So, a quantity of 7 will get the price from threshold 5 as against 10.
Few guidelines on solving these challenges:
Although the above problem might appear simple, the solution is not so straightforward.
- Use a variety of formulas: Do not just rely VLOOKUP. Instead experiment with formulas like SUMIF, COUNTIF, INDEX, MATCH etc. to get results
- Use helper columns: Break down the problem in to several steps and use helper columns to get the results
- Use pen & paper: Write down the logic first, then simulate it in excel using formulas. It clears your mind fast.
- Many solutions exist: Each problem can be solved in several different ways. So once you find a solution, feel free to explore other options
- Share your solutions: Use comments box to share your solutions with us. I am always looking for new ways to solve problems. So teach me…
Solution to the Challenges:
Here is a workbook with one set of solutions for the problems. As I said, many other solutions do exist. So use this workbook as an indication of what is possible.
Click here to download excel workbook with all the data for these challenges.
One Link to More VLOOKUP Awesomeness:
Debra at Contextures has chipped in with some interesting videos on VLOOKUP formulas. Check them out here.
The 2nd Joke:
It is quite difficult to set an expectation and then meet it. More so with jokes. But do you know that Chandoo.org’s 404 pages show Excel error messages? For example go to http://chandoo.org/wp/missing_file/. Refresh the page to see a different message. 🙂
It is Diwali (the festival of lights) in India this weekend. So I am going to spend time with family, light some fireworks and relax. I wish you a happy Diwali if you celebrate one. Even otherwise, I wish a lot of light and warmth in to your life this year.
14 Responses to “Group Smaller Slices in Pie Charts to Improve Readability”
I think the virtue of pie charts is precisely that they are difficult to decode. In many contexts, you have to release information but you don't want the relationship between values to jump at your reader. That's when pie charts are most useful.
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Chandoo,
millions of ants cannot be mistaken.....There should be a reason why everybody continues using Pie charts, despite what gurus like you or Jon and others say.
one reason could be because we are just used to, so that's what we need to change, the "comfort zone"...
i absolutely agree, since I've been "converted", I just find out that bar charts are clearer, and nicer to the view...
Regards,
Martin
[...] says we can Group Smaller Slices in Pie Charts to Improve Readability. Such a pie has too many labels to fit into a tight space, so you need ro move the labels around [...]
Chandoo -
You ask "Can I use an alternative to pie chart?"
I answer in You Say “Pie”, I Say “Bar”.
This visualization was created because it was easy to print before computers. In this day and age, it should not exist.
I think the 100% Bar Chart is just as useless/unreadable as Pies - we should rename them something like Mama's Strudel Charts - how big a slice would you like, Dear?
My money's with Jon on this topic.
The primary function of any pie chart with more than 2 or 3 data points is to obfuscate. But maybe that is the main purpose, as @Jerome suggests...
@Jerome.. Good point. Also sometimes, there is just no relationship at all.
@Martin... Organized religion is finding it tough to get converts even after 2000+ years of struggle. Jon, Stephen, countless others (and me) are a small army, it would take atleast 5000 more years before pie charts vanish... patience and good to have you here 🙂
@Jon .. very well done sir, very well done.
good points every one...
I've got to throw my vote into Jon's camp (which is also Stephen Few's camp) -- bars just tend to work better. One observation about when we say "what people are used to." There are two distinct groups here (depending on the situation, a person can fall in either one): the person who *creates* the chart and the person who *consumes* the chart. Granted, the consumers are "used to" pie charts. But, it's not like a bar chart is something they would struggle to understand or that would require explanation (like sparklines and bullet graphs). Chart consumers are "used to" consuming whatever is put in front of them. Chart creators, on the other hand, may be "used to" creating pie charts, but that isn't an excuse for them to continue to do so -- many people are used to driving without a seatbelt, leaving lights on in their house needlessly, and forwarding not-all-that-funny anecdotes via email. That doesn't mean the practice shouldn't be discouraged!
[...] example that Chandoo used recently is counting uses of words. Clearly, there are other meanings of “bar” (take bar mitzvah or bar none, for [...]
[…] Grouping smaller slices in pie chart […]
Good article. Is it possible to do that with line charts?
Hi,
Is this available in excel 2013?