## Is this dataviz?

##### Jun 25, 2024

The message in this Visual Capitalist chart is simple - that big tech firms are spending a lot of cash buying back their own stock (which reduces the number of shares in the market, which pushes up their stock price - all without actually having improved their business results.)

But is this data visualization? How does the visual design reflect the data?

The chart form is a half-pie chart, composed of five sectors, of increasing radii. In a pie chart, the data are encoded in the sector areas. But when the sectors are of different radii, it's possible that the data are found in the angles.

The text along the perimeter, coupled with the bracketing, suggests that the angles convey information - specifically, the amount of shares repurchased as a proportion of outstanding share value (market cap). On inspection, the angles are the same for all five sectors, and each one is 180 degrees divided by five, the number of companies depicted on the chart, so they convey no information, unless the company tally is deemed informative.

Each slice of the pie represents a proportion but these proportions don't add up. So the chart isn't even a half-pie chart. (Speaking of which, should the proportions in a half-pie add up to 100% or 50%?)

What about the sector areas? Since the angles are fixed, the sector areas are directly proportional to the radii. It took me a bit of time to figure this one out. The radius actually encodes the amount spent by each company on the buyback transaction. Take the ratio of Microsoft to Meta: 20 over 25 is 80%. To obtain a ratio of areas of 80%, the ratio of radii is roughly 90%; and the radius of Microsoft's sector is indeed about 90% of that of Meta. The ratio between Alphabet and Apple is similar.

The sector areas represent the dollar value of these share buybacks, although these transactions range from 0.6% to 2.9% as a proportion of outstanding share value.

Here is a more straightforward presentation of the data:

I'm not suggesting using this display. The sector areas in the original chart depict the data in the red bars. It's not clear to me how the story is affected by the inclusion of the market value data (gray bars).