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Bayesian Evaluation of Transplant Center Outcomes

Bayesian Evaluation of Transplant Center Outcomes. Mark A. Schnitzler, Ph. D. What the Heck is an O/E Ratio Anyway?. Why Should You Care?. You’ve been held to an O/E ratio standard That exact same O/E ratio is sticking around, at least for now All that’s changing is the test.

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Bayesian Evaluation of Transplant Center Outcomes

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  1. Bayesian Evaluation of Transplant Center Outcomes Mark A. Schnitzler, Ph. D.

  2. What the Heck is an O/E Ratio Anyway?

  3. Why Should You Care?

  4. You’ve been held to an O/E ratio standard • That exact same O/E ratio is sticking around, at least for now • All that’s changing is the test

  5. Craps Odds with Fair Dice

  6. How Can We Tell if the Dice are Weighted? After 72 Rolls

  7. O/E for Craps • O = 4 • E = the sum of probabilities of craps for each roll. • 1/36th x 72 = 2 • Is the house cheating you? • One way to find out: • Is O/E too big?

  8. Craps Rolled Craps Rolled

  9. Craps Rolled Craps Rolled

  10. What’s Wrong With the Traditional Method • Arbitrary criteria not based on statistical theory • For volumes < 10 • One event • For all others • O-E > 3 • O/E > 1.5 • p-value < 0.05 (one sided Poisson distribution)

  11. Why Did We End up with Arbitrary Rules? • Using Poisson distributions to test O/E ratios is an old method from Epidemiology • The Poisson distribution was developed to describe the number of time a mule would kick a person during a short period of time • Large E wasn’t what it was made for • Very sensitive at large E • O/E > 1.5 • Not sensitive at all at very small E • One event flags a center with fewer than 10 patients • O-E > 3? • Politics

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