Transcript Sample size issues in avian epidemiology: a data

Determining sample size for avian mortality
(and vice-versa)
- using data augmentation for epidemiology
Ken Rice1,2, Thomas Lumley1,3 , Betz Halloran1,4
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University of Washington, Department of Biostatistics
Seattle Symphony Chorale
Seattle Choral Company
Statistical and Quantitative Methods for Infectious Diseases and
Evaluating Interventions
West Nile Virus
• King County wants you to be aware!
It’s working!
• Cases of West Nile in King County
0.39
0.26
Horses
Humans
Birds
0.13
0
2002
2003
2004
2005
2006
2007
Avoiding misclassification
“If you find a dead crow, blue jay, raven or pigeon”
Before analyzing it;
• Is it a bird?
• Is it a plain (bird)?
• Is it dead?
Sample size – a reminder
• Power is low for rare events
• Low power =
lots of awkward questions to answer!
• How to increase sample size of dead
birds?
Sample size – a reminder
• A hint!
cyanide
strychnine
• We don’t cover this in Autumn quarter,
or Winter…