When discussing health insurance we frequently hear that there are “46 million uninsured” in America. This figure is from a monthly survey of about 50,000 households done by the Bureau of Labor Statistics and the Census Bureau. This Current Population Survey (CPS) then uses statistical techniques to paint a picture of the entire U.S. population.

Advocates for expanding taxpayer-subsidized health insurance, and their allies in the press, repeat this 46 million number constantly. It paints the following technically accurate but misleading picture:

This looks really bad. At least there are more than 250 million people with health insurance – that is clearly a good thing that we never hear it in the press. Still, there’s a lot of red there. It means that in 2007 (15%) of Americans lacked health insurance, according to the CPS. Advocates, some elected officials, and the press round that number up to “1 in 6 Americans.” We hear that there are “46 million uninsured,” and then we jump to the conclusion that government needs to help 46 million people buy health insurance, subsidized by taxpayers.

Let’s look inside that 45.7 million number and see what we can learn. Here is our key graph:

First, I need to make a technical disclaimer. I had this same detailed breakdown for 2005 data, done by health experts when I was part of the Bush Administration. I now have a 2007 total (45.7 million), and so I have proportionately adjusted the components to match that new total. It is a back-of-the-envelope calculation, but I am confident that it is solid, and it does not move any component by more than two hundred thousand. In addition, the expert analysis I am using ensures that the subdivisions shown above do not overlap. I will slightly oversimplify that point in the following description of the breakdown to make the explanation readable.

Let us walk through the graph from top to bottom.

• There were 45.7 million uninsured people in the U.S. in 2007.
• Of that amount, 6.4 million are the Medicaid undercount. These are people who are on one of two government health insurance programs, Medicaid or S-CHIP, but mistakenly (intentionally or not) tell the Census taker that they are uninsured. There is disagreement about the size of the Medicaid undercount. […]