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I have some data that I'm trying to represent in a visualization with a week-over-week change. So the source can be something like:

Fruit    This Week   Last Week  Delta   Proportion    
--------------------------------------------------
Bananas     10           8         2        25%
Oranges     110         100        15       15% 
Apples      400         390        10      2.6%

What are some ways that I can effectively show that even though Bananas increased by 25% (technically the "biggest mover" of the week) it's an increase that is "overstated" because of the small overall numbers of bananas sold? I think I need a scaling approach of some sort but can't quite figure it out.

I_Play_With_Data
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2 Answers2

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Seems like you want to show both percentage and magnitude at the same time.

I would then suggest that you plot the two values for comparison.

You could plot all in one chart with two axes:

enter image description here

or split it into two charts:

enter image description here

both visualizations make clear that Bananas have the largest increase, while Apples is the fruit that sells the most.

Bruno Lubascher
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  • I should have clarified that I want to express this in some sort of numeric value – I_Play_With_Data Aug 06 '18 at 18:51
  • @UnknownCoder I would still give you a similar answer. You want to show two perspectives of your data. You want to show % grow in the group and scale according to magnitude, you cannot put that into a single number.

    You could say: Grow in Banana (25% out of 8 units), Oranges (10% out of 100 units) Apples (2.56% out of 390 units).

     – Bruno Lubascher Aug 07 '18 at 06:51
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Add everything up from first week 8 + 100 + 390 = 498 and second 10 + 110 + 400 = 520.

The share of overall sales for Bananas in the first week is 8 / 498 = 1.6% of sales and next week it was 10 / 520 = 1.9%, so Bananas grew by 0.3% overall sales - which is a bit misleading, but that is what you're after.

Silent M
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  • If there was no change in the number of bananas sold from last week to this week, then you would expect a change of $0%$. But this metric would show a decrease in bananas. – Bruno Lubascher Aug 07 '18 at 11:54
  • @Bruno: The metric shows the change of the banana share. When they don't change, but the total increases, the bananas decrease. This is correct if considering what is actually measured. – Eulenfuchswiesel Aug 07 '18 at 14:26
  • @Eulenfuchswiesel my comment is to compare the proposed answer with the OP question. OP wrote even though Bananas increased by 25% (technically the "biggest mover" of the week) it's an increase that is "overstated". Seems like he still wants to keep the sign of the individual items change. – Bruno Lubascher Aug 07 '18 at 14:32
  • @BrunoGL Well, but the biggest mover is because it's relative to itself. The only thing you can do is to put Bananas against everything, resulting in minor change, or even decrease if other things would grow... – Silent M Aug 07 '18 at 15:09
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    @SilentM, you answer is totally valid, it will really depend on what the OP needs this number for in the end. – Bruno Lubascher Aug 07 '18 at 19:18