The Center for Medicare and Medicaid Services (CMS) recently released some new data files on plan level enrollment in the states that operate their own marketplaces (SBMs) instead of using Healthcare.gov. I’m just scooting and scouting around in the data right now. And there is something odd for the 2019 data.

For the states that operate a state based marketplace in 2019, over half of their Plan IDs have enrollment suppressed. This is ODD! CMS has a policy of suppressing enrollment data in a cell whenever that cell is either less than 11 or an ambitious researcher can use the data in a cell to calculate precisely what is in a suppressed cell.

Let’s take an example:
Total: 199
A: 9
B: 90
C: 100

In this case, CMS will report Total and Column C while suppressing A because it is under 11 and B because it is one degree of freedom where an actual number allows us to calculate A.

But this is weird!

Some of the suppression is to help hide low count cells. But most of this is likely low cells. Building a plan is not free. There are non-zero actuarial consulting costs to price a plan and then a decent amount of administrative hassle and costs to file a plan and build the benefits into the claims system. Building a new plan configuration into the claims system and then using that specific build for seven people is highly unlikely to be cost-effective.

I’m not sure why so many SBM plans are suppressed for likely low enrollment… but this is just odd and worth keeping an eye on.