Photographer: Daniel Acker/Bloomberg
Photographer: Daniel Acker/Bloomberg

Last week, I posted this chart:

Gallup index
Gallup index

This morning, Vox.com, Ezra Klein’s new venture, tweeted:

Vox chart
Vox chart

That is interesting. But to me, it’s not so much interesting because of the comparison to 2009, but because of the comparison to last week's chart.

Basically, Gallup reports quarterly numbers, though during the current quarter, it polls continuously and updates monthly. The numbers I posted last week were for January, and they showed that 16 percent of the population was uninsured. The numbers Vox tweeted this morning were from Gallup’s latest numbers, which include February.

What this suggests is that if Gallup’s numbers are accurate -- and that’s a big if, which I’ll get to in a minute -- then most of the decline in the number of uninsured came from October to January. Now it’s leveling off -- still decreasing, but much more slowly.

Why is that significant? Well, let’s look at the pattern of enrollment:

Exchange Signups
Exchange Signups

The big spike in enrollment came in December. And the working assumption has been that that spike represented a lot of people who already had insurance, plus some older and sicker people who had been unable to buy insurance in the private market.

Why was that the operating assumption? Well, for one thing, surveys such as McKinsey & Co.'s seemed to show that most of the people buying already had insurance; so did reports from industry expert Bob Laszewski. For another thing, the demographics of the folks buying insurance skewed old: Fewer than 25 percent were young adults. For reference, the Barack Obama administration has said that about 40 percent of the market has to be young, healthy adults in order to make the new exchange plans actuarially sound.

So my general assumption -- which is also what a lot of other people are assuming -- is that the “young invincibles” are going to show up later. Unlike the sick or the previously insured who wanted to maintain continuous coverage, the young invincibles do not feel an urgent need for insurance. Maybe they’ll get around to it, but they weren’t rushing to make a December deadline.

What the Gallup numbers suggest is that instead of ramping up their purchases, that critical group of young, uninsured people may actually be slowing them down; the percentage of uninsured in the population barely budged from January to February, after showing big drops from October to January.

However, that observation comes with a big caveat. The Gallup number tends to jump around a lot, as you can see if you look at the graph -- it’s what statisticians call “noisy.” I frankly suspect that the 18 percent figure is just a statistical outlier, and the true number was probably closer to the 17.1 percent reported in the second and fourth quarters of 2013. Which would mean that the number of uninsured dropped about 1.1 percent, not 2 percent, between the beginning of open enrollment and January, when the first policies went into effect. Which in turn would make a 10 basis point drop between January and February look a little more significant, though still worrisome.

However, we should also remember that the most recent numbers are noisy -- even more than those in the previous quarters, because they haven’t finished polling. So 15.9 percent might be the true number, or it might be too high, or too low.

Still, that’s the data we have, and with the appropriate caveats, it’s useful information. The more useful information, of course, will come after we have total enrollments and the U.S. Census Bureau takes a crack at estimating the uninsured.

To contact the writer of this article:
Megan McArdle at mmcardle3@bloomberg.net.

To contact the editor responsible for this article:
James Gibney at +1-202-624-1863 or jgibney5@bloomberg.net.