Mix percent metaphors, add average confusion, and serve

Mar 27, 2013

Sometimes, a chart just strains your mind. Such is the case with the following, a tip from Augustine F. (@acfou)

There are just so many percentages on the chart it's really hard to figure out which is which.

Under the title, it hints that they are showing results from a poll. The legend implies that the poll asks for estimates of budget and revenue allocations: one imagines the questions were what proportion of your marketing budget is allocated to digital? and what proportion of your revenues is attributed to digital? On top of the bars are some percentages, presumably percentages of respondents. Perhaps, or perhaps not. The column labels clearly add up to over 100% since there are two columns in the 30-35% range.

Under the axis, we have buckets of percentages. Are they percentages of people, of budgets or of revenues? Why and how are they bucketed?

My best guess is that the survey is a multiple-choice with 11 choices corresponding to the groups of columns. The axis labels refer to both percentage of budget and percentage of revenues, depending on which column you're looking at.

What is maximally confusing is the last set of columns, labeled "Average", with values in the 35% range. It is most likely not a choice in the survey. They somehow came up with an average based on the responses. So maybe I was wrong about the multiple-choice format: if the raw data comes in buckets like 61 to 70%, there is no easy way to average these responses. Maybe they asked for two exact percentages, and then grouped them afterwards.

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To sum all that up, the percentages on top of the columns are percentages of respondents, except in the last set of columns, where they are percentages of budget (or revenues). The percentages of budget (or revenues) are sitting on the horizontal axis, except in the last label, called "Average", where it means the average respondent.

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There is a problem with my interpretation. It makes the chart completely worthless!

What use is it to learn that "16% of the respondents say they allocate 11-20% of their budget on digital while 12% of the respondents say they derive 11-20% of their budget from digital"?

You might be interested in whether there is a return on investment to the money spent on digital marketing. You'd then need to know for a given company, what proportion of budget was spent on marketing versus what proportion of revenues was attributed to that marketing. In this chart, there is no linkage -- the companies who say they spend 11-20% on digital may or may not be the same set of companies who say they derive 11-20% from digital spend.

If the survey asked for exact percentages, then I'd prefer to see a scatter plot, showing proportion of budget on one axis, and proportion of revenues on the other axis, each dot representing a respondent.

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A final note: it is worth asking what types of people answer this survey. Pretty much the only people in a company who can answer this question accurately are the heads of marketing. If you are working for the head of marketing, you likely know the details of a particular segment of marketing but not the aggregate numbers. If you work in a different department, there is little to no chance that you have any useful knowledge about marketing budgets and revenue allocations.

One would also appreciate it if all such pictures include the sample size.

I went to the dot com website referenced in the lower left of the chart. Dear me, to think that such a collection of basic Excel templates is an entire company putting its best foot forward!

And yet, I regularly get visited by the latest consultants our directors have hired, so I can help them make a standard bar or pie chart, so they can take it back with a fat invoice attached. Maybe I should get into that racket.

Great post.
I wonder how many of the respondents were 1-man shows?

This is a chart from The Economist about GDP world change:
http://www.economist.com/news/economic-and-financial-indicators/21574491-world-gdp
I am unable to understand what piles represent.
World GDP change is given by GDP(final)/GDP(initial)-1. It is a weighted average of the different area GDP changes. But why does it appear nearly as the sum of the area GDP changes?
Sum of percentage or average of percentages? This is the dilemma.

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