When I recently published the latest edition of The Data & Analytics Dictionary, I included an entry on Charts which briefly covered a number of the most frequently used ones. Given that entries in the Dictionary are relatively brief ^[1] and that its layout allows little room for illustrations, I decided to write an expanded version as an article. This will be published in the next couple of weeks (UPDATE: now published as A Picture Paints a Thousand Numbers).

One of the exhibits that I developed for this charts article was to illustrate the use of Bubble Charts. Given my childhood interest in Astronomy, I came up with the following – somewhat whimsical – exhibit:

Bubble Charts are used to plot three dimensions of data on a two dimensional graph. Here the horizontal axis is how far each of the gas and ice giants is from the Sun ^[2], the vertical axis is how many satellites each planet has ^[3] and the final dimension – indicated by the size of the “bubbles” – is the actual size of each planet ^[4].

Anyway, I thought it was a prettier illustration of the utility of Bubble Charts that the typical market size analysis they are often used to display.

However, while I was doing this, my older daughter wandered into my office and said “look at the picture I drew for you Daddy” ^[5]. Coincidentally my muse had been her muse and the result is the Data Visualisation appearing at the top of this article. Equally coincidentally, my daughter had also encoded three dimensions of data in her drawing:

1. Rank of distance from the Sun
2. Colour / appearance
3. Number of satellites ^[6]

She also started off trying to capture relative size. After a great start with Mercury, Venus and Earth, she then ran into some Data Quality issues with the later planets (she is only four).

Here is an annotated version:

I think I’m at least OK at Data Visualisation, but my daughter’s drawing rather knocked mine into a cocked hat ^[7]. And she included a comet, which makes any Data Visualisation better in my humble opinion; what Chart would not benefit from the inclusion of a comet?
 

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Notes

[1]	For me at least that is.
[2]	Actually the measurement is the closest that each planet comes to the Sun, its perihelion.
[3]	This may seem a somewhat arbitrary thing to plot, but a) the exhibit is meant to be illustrative only and b) there does nevertheless seem to be a correlation of sorts; I’m sure there is some Physical reason for this, which I’ll have to look into sometime.
[4]	Bubble Charts typically offer the option to scale bubbles such that either their radius / diameter or their area is in proportion to the value to be displayed. I chose the equatorial radius as my metric.
[5]	It has to be said that this is not an atypical occurence.
[6]	For at least the four rocky planets, it might have taken a while to draw all 79 of Jupiter’s moons.
[7]	I often check my prose for phrases that may be part of British idiom but not used elsewhere. In doing this, I learnt today that “knock into a cocked hat” was originally an American phrase; it is first found in the 1830s.

Another article from peterjamesthomas.com. The home of The Data and Analytics Dictionary, The Anatomy of a Data Function and A Brief History of Databases.

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