Monday, July 4, 2016

Understanding children's heart surgery outcomes

Good data should inform our decisions. Even really stressful decision. This site demonstrates this beautifully by providing UK pediatric hospital survival rates to aid the parents of children undergoing heart surgery.

The information is translates for lay people. They present statistical ideas that you and your students have heard of, but without a lot of statistical jargon. The data is also presented very clearly. They present detailed hospital survival rates which includes survival ranges:

So, it contains data from a given time period. It includes the actual mortality rate as well as a range that is likely to contain the true mortality rate. Essentially, confidence intervals but not exactly confidence intervals.

In addition to this more traditional presentation of the data, the survival ranges are explained in greater detail in a video. I think this video is useful in that it explains distribution of the sample mean and how to use these in order to make an estimate of true survival rates.

Examples for the classroom:

-Sample v. population: A 30 day survival sample rate is just a sample and does not necessarily reflect the True outcome data.
-Variability: They explain that the data contains variability due to the fact that all patients have different pre-existing conditions/personal odds of survival.
-Confidence intervals-ish: When they describe a given survival rate, they use that within the context of that hospitals predicted range. These "predicted ranges" are confidence intervals. They never, ever call them confidence intervals because that phrase means nothing to a lay person.
-When computing the predicted range, they create multiple models of possible samples that could have been collected. So the sampling distribution of the sample mean.
-The blue bar is the 95th percentile. The gray bar is the 99.8th percentile.
-Again, data shouldn't be collected and left on a shelf or in a difficult to follow medical journal. It should be shared with the people that need it the most so they can make an informed decision about their child's health.