19-21 Modern advances - Researcher and statistician error...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Researcher and statistician error ~8% of biomedical papers have substantial statistical flaws 2 Publication bias Papers are more likely to be published if P <0.05 This causes a bias in the science reported in the literature. Computer-intensive methods ! Hypothesis testing: ! Simulation ! Randomization ! Confidence intervals ! Bootstrap Simulation ! Simulates the sampling process on a computer many times: generates the null distribution from estimates done on the simulated data ! Computer assumes the null hypothesis is true
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ratios Social spiders live in groups Example: Social spider sex ratios ! Groups are mostly females ! Hypothesis: Groups have just enough males to allow reproduction ! Test: Whether distribution of number of males is as predicted by chance ! Problem: Groups are of many different sizes ! Binomial distribution therefore doesn’t apply Simulation: ! For each group, the number of spiders is known. The overall proportion of males, p m , is known. ! For each group, the computer draws the real number of spiders, and each has p m probability of being male. ! This is done for all groups, and the variance in proportion of males is calculated. ! This is repeated a large number of times. 0.5 1. 1.5 2. 2.5 3. 3.5 200 400 600 800 1000 Variance in proportion of males (Pseudo-values) Frequency Actual Observed Value (0.44) The observed value (0.44), or something more extreme, is observed in only 4.9% of the simulations. Therefore
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/16/2010 for the course MATHEMATIC 1231 taught by Professor Driscoll during the Spring '10 term at Clayton College of Natural Health.

Page1 / 10

19-21 Modern advances - Researcher and statistician error...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online