|Obama's Health Law|
The next step in an analysis like this could be to eventually reveal what plans people are buying, as there are critical differences between a Bronze and a Platinum plan. It's great news that the percentage of people who lack health insurance is dropping, but it wouldn't be so good if most of them are buying Bronze plans, as those only cover 60% of the price of your medical bills, on average. Hardly something an advanced democratic society could feel proud of.
By the way, and just to be picky: I missed confidence intervals. The numbers displayed on the story and on the map are based on a predictive model, so there must be some amount of error, even if the survey's sample is really big. You can read a detailed description of the statistical calculations here.