significance of statistical significance

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Post on 30-Nov-2014




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Keynote presentation this classic paper: Sterne JAC, Smith GD (2001) Sifting the evidence - what's wrong with significance tests? British Medical Journal 322: 226-231.


  • 1. signicant evidence
  • 2. what is a p-value?when is a p-value appropriate?what are good solutions?
  • 3. p-value is the measure of strength of evidence against thenull hypothesis.Smaller values the stronger the evidence against null.
  • 4. unfortunately, the p-value used in environmental science istheType I error rate.
  • 5. why does using p-values matter?no strength of evidence conveyed, i.e. treatment strength.
  • 6. why does using p-values matter?scales up to population level false positives
  • 7. p-values are acceptable if ... there are not a large populationof studies, the experiment is very controlled, and the value isvery, very low.provides a plausible range.
  • 8. solutionspresent precise p-valueinterpret based on context, experiment, & evidencedo not interpret as signicant/non-signicantreport strength of effectsshow condence intervals
  • 9. ultimately, the goal is manage & seek evidence
  • 10. resourcesSterne JAC, Smith GD (2001) Sifting the evidence - whatswrong with signicance tests? British Medical Journal 322:226-231.


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