In between the election news: waterfall charts….

Waterfall charts are a great tool to explain the difference between 2 scenarios. In SlideMagic, they are really easy to create. Below is one I put together quickly with data from Apple’s 2020 Q4 earnings result, and a photo I found using SlideMagic’s built-in Unsplash image search. Notice how I opted for an unusual vertical waterfall, to create more space for the axis labels.

Some people would argue that you could make the chart even clearer by breaking the axes: showing them as ‘5.6’ and ‘4.7’ for example. Yes, it would highlight the deltas better, but in general, I think manipulating axes, well, manipulates the message. The fact that the changes are relatively small to the total is part of the message.

I reshuffled the rows a bit to group the decreases and increases. That makes it more clear in one sense, but less clear in another. Your choice.

\How do you go about making such an analysis? I put my numbers in a Google Sheet that you can view yourself.

1. Enter the data for the 2 comparable quarters in 2 columns. Add the totals as calculations rather than hard-coded numbers to check that you did not make any typos. (The blue cells are the one that I type in, the white ones are calculations).

2. Create space between the 2 columns

3. Pull numbers from the input that you consider drivers. You see that I deviated a bit from the way the input was presented:

   1. Divided billions by thousands to make it more readable

   2. I use % gross margin rather than absolute COGS and profit numbers

   3. R&D: absolute number, SGA, % of sales

4. Recalculate the operating income with just these drivers (line 37), it is crucial that you get this right, double check with the input.

5. Now start varying your drivers one at a time, and recalculate the operating income in the scenario that just that one variable would have changed (see the green numbers in the spreadsheet).

6. Finally, check whether the component variations add up to the total variation you need to explain (in this case, I was lucky). If you are not, you need to allocate the non-explained differences to the factors somehow.

It is important to keep in mind that these spreadsheet figures are just spreadsheet figures. The change in product gross margin for example is probably not independent from the change in product mix (fewer phones, more laptops). Also there is a small rounding issue (the rounded vales do not add up to 14.8). I would solve that by chopping the biggest factor (-1.7 to -1.6). It is always distracting when small rounding errors create inconsistent numbers on your slide.

Users of SlideMagic can access the waterfall charts with a search for ‘apple’ in the desktop app.