Depicting imbalance, straying from the standard chart
Sep 19, 2016
My friend Tonny M. sent me a tip to two pretty nice charts depicting the state of U.S. healthcare spending (link).
The first shows U.S. as an outlier:
This chart is a replica of the Lane Kenworthy chart, with some added details, that I have praised here before. This chart remains one of the most impactful charts I have seen. The added time-series details allow us to see a divergence from about 1980.
The second chart shows the inequity of healthcare spending among Americans. The top 10% spenders consume about 6.5 times as much as the average while the bottom 16% do not spend anything at all.
This chart form is standard for depicting imbalance in scientific publications. But the general public finds this chart difficult to interpret, mostly because both axes operate on a cumulative scale. Further, encoding inequity in the bend of the curve is not particularly intuitive.
So I tried out some other possibilities. Both alternatives are based on incremental, not cumulative, metrics. I take the spend of the individual ten groups (deciles) and work with those dollars. Also, I provide a reference point, which is the level of spend of each decile if the spend were to be distributed evenly among all ten groups.
The first alternative depicts the "excess" or "deficient" spend as column segments.
The second alternative shows the level of excess or deficient spending as slopes of lines. I am aiming for a bit more drama here.
Now, the interpretation of this chart is not simple. Since illness is not evenly spread out within the population, this distribution might just be the normal state of affairs. Nevertheless, this pattern can also result from the top spenders purchasing very expensive experimental treatments with little chance of success, for example.