Bill prognosis gets a few improvements

Back in April we introduced “bill prognosis” (original post), a statistical analysis of how likely bills are to be enacted. Today we’re making a few improvements. Read on for more about it.

For each bill (example: S. 3637), we compute a probability that the bill will be enacted and show the factors that help or hurt the bill’s chances of survival. In the 2009-2010 Congress, only 3% of bills were enacted. The prognosis has helped GovTrack users identify which of the 10,000+ bills to pay attention to — those with probabilities higher than 3% — and it has provided important new context to the legislative process.

Last weekend I came across an academic paper (Yano, Smith, and Wilkerson 2012) on exactly this subject (thanks to Rob Richards for pointing it out to me). The methodology in the paper is remarkably similar to what we do to compute bill prognosis, which is reassuring. Wilkerson, the third author, has been doing interesting research on the legislative process for many years.

The paper had a good idea which I hadn’t thought of: using when during the Congressional session a bill was introduced to help predict its outcome. They found that bills introduced in the first year of the two-year Congressional session are more likely to make it out of committee.

So I’m adding three new factors to GovTrack’s analysis: whether the bill was introduced in the first 90 days of the Congress, whether it was introduced in the first year, and whether it was introduced in the last 90 days of the Congress. You can now see that last one in the factors for S. 3637, for example.

I found that these factors have a complex relationship with a bill’s outcome:

  • Bills introduced in the first 90 days are a little more likely to make it out of committee. This makes sense since they have more time to be deliberated than bills introduced later in the session.
  • Bills introduced in the last 90 days are less likely to make it out of committee, which makes sense for the same reason. But of those that do, they are much more likely to be enacted.

In other words it helps to introduce bills early, but we should not discount the late-breaking bills at the end of a Congress. Some of those bills will get rushed through committee, and if they do it is probably because they are the result of successful negotiations that paved their way to final passage.

The other change to the prognosis is that we now compute two probabilities for each bill, one that the bill will make it out of committee and one that it will be enacted (or for simple/concurrent resolutions, agreed to). If one probability was good, two must be better! You can see that, for example, on H.R. 6140.


  1. I think you guys are doing fantastic job, I have been on the site every day to see what our tax dollars are doing and where the country is headed for. Keep up the good work. I hope you will do more to help us Americans keep tab on the politicians.

    A suggestion, you should do the same but track the white house and every agency that reports to the white house, due to the extreme regulatory steps that all agencies are taking in order to by pass the congress and be accountable.


  2. I’m done with every member of the US congress. DONE. When they turned their backs on the people on the east coast, victims of Sandy, they showed their true colors and nothing will ever convince me that they are not the most uncaring and shallow people ever to exist. NOTHING. I’m DONE with them all.


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