Statistics you can use: Practical use of statistics in reading medical research literature. PAS 610 June 21, 2005 Robert D. Hadley PhD, PA-C. The basics:. “There are three kinds of lies: lies, damned lies, and statistics.” Benjamin Disraeli, British politician (1804 - 1881).
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Statistics you can use:Practical use of statistics in reading medical research literature
June 21, 2005
Robert D. Hadley
Quartiles, tertiles, etc.
Parametric vs. Nonparametric
1- vs. 2-tailed
Type I (alpha)
Incorrectly reject the null hypothesis
Infer that something is significant when it is not
Type II (beta)
Incorrectly accept the null hypothesis
Infer that something is not significant when it really is
So, which is better to do?
Which way does “intention to treat” skew the inference?
Note: “normal” range for lab tests is ± 2 s.d.
What do unequal CI bars mean?
BMJ 2002; 324:71-86
Bortezomib or High-Dose Dexamethasone for Relapsed Multiple Myeloma
N Engl J Med 2005;352:2487-98
36% RRR nonfatal MI + fatal CHD
Atorvastatin 10 mg No. of events: 100
Placebo (diet and exercise only)No. of events: 154
All patients counseled on
diet and exercise
Cumulative incidence (%)
What is approximate NNT for 1 year?
Sever PS et al. Lancet. 2003;361:1149-1158.
ROC value: 0.65 (0.61-0.70)
25th percentile, median and 75th percentile indicated in each box
Nissen et al, N Engl J Med 2005;352:29-38