Using spots and rings in tables

jenmoocat in comments asks about the "spot matrix" table I used to display the scores from one to ten of X options in Y categories. My technique has always been about using bubble charts, in a similar way to this heatmap tutorial at More Information Per Pixel. Chandoo at Pointy Haired Dilbert describes a different way, using a table and the Wingdings 2 font.

This is a great alternative, and would work really well in a dashboard. Five separate score levels is about the maximum that people can easily distinguish anyway. After that, you're relying more on the approximate response to levels of darkness to guide the eye. It becomes less of a table and more of a map.

Those curious about the history of such tables should have a look at page 174 of Edward Tufte's 1983 classic Visual Display of Quantitative Information, where Tufte shows and praises a Consumer Reports small multiple of tables of cars and their repair trouble spots by make and year. Tony Rose of DSA Insights points out that this is a sophisticated version of Harvey Balls, made less qualitative and more quantitative.

Edited to add: Thinking about the design of Chandoo's table some more, if you want to try his technique out in your own tables, bring the spots closer together, so that they appear to be words in a sentence. They'll be easier to read that way. And as there are only five columns in the example, if you bring them still closer, they can be like letters in a word, and "read" at a glance. Narrowing the table may require abbreviating the titles or turning them on their side, but I think it's worth it.

The design philosophy to follow is one similar to Tufte's "sparkline" philosophy, that a tiny picture is like a word, and should be presented at a similar typographical density. Stringing them out is liable to make it harder to see the patterns.

If you want to avoid privileging one orientation, you'll want the lines to be no further apart from each other than the spaces between columns. If you have only one row, consider abandoning spots altogether, and go for a tiny bar-graph sparkline instead. Gauging the relative value of circular spots is a problem, because you're asking the reader to judge areas, which are lower in Cleveland's Hierarchy than lengths. Their symmetry is only an advantage if the table is two-way, where columns would be harder to read up and down.

Clock this

Jon Peltier has written about graphs based on hours of the day (and chosen the perfect title, so I have to make do with second best), with examples attempting to show the day and night cycles together intuitively.

I think the whole day-night split thing is artificial: there's no connection between the times that are twelve hours apart and happen to have the same number under our old mediæval twelve hour day, twelve hour night scheme. I'm surprised how much less Americans use the 24 hour clock, and how they call it "military time" when they do. In Britain we associate it more with the coming of the railways in the nineteenth century, and the need for standard timetables (until trains made national time zones necessary, individual towns had their own time!) I've made a polar area graph on a 24 hour scheme here:
The polar area graph is one of my favourite neglected specialist graph types, but it really only has a chance of being the graph type of choice if

a) you don't mind reading stacked areas instead of position along a common scale (see Cleveland's Hierarchy),
b) the data set is truly cyclic, not linear, and
c) there are two series to compare, one much smaller than the other (here we lack a second, smaller series that could be plotted closer to the centre, to take advantage of the square root relationship between the area of the slices and their radius)