Difference between revisions of "Sandbox"

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     <td> <div align="center">28</div></td>
 
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     <td> <div align="center">82</div></td>
     <td> <p align="center">..</p>
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     <td> <p align="center">.3415</p>
 
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Revision as of 14:14, 13 September 2009

Breaking News

The Wall Street Journal of September 8, 2009 reports on a study in the Journal of Bone and Joint Surgery: “The researchers compared the outcomes of patients who underwent surgery between 6 a.m. and 4 p.m. for fractures of the femur or tibia to those who had comparable surgeries for similar fractures outside those normal hours.”

The results are:

Difference = p (1) - p (2) Estimate for difference: 0.170035 95% CI for difference: (0.0346494, 0.305420) Test for difference = 0 (vs not = 0): Z = 2.37 P-Value = 0.018

Fisher's exact test: P-Value = 0.026

Discussion

1. Why is the Fisher exact test P-Value (0.026) to be preferred to the other P-Value mentioned (0.018)?

2. The Wall Street Journal mentioned several caveats “making it difficult to determine the underlying reasons for the after-hours patients’ poor outcomes.” List a few practical significance hedges to the statistically significant result.

Sample

Reoperations

Needed

Sample Size
Sample Proportion
Outside Normal Hours
28
82

.3415

Within Normal Hours
12
70
.1714