Experimental Design Jan 9, 2004 Stats 11, Winter 2004 Experimental Design Jan 9, 2004

London Cholera Outbreak, 1854 Cholera kills quickly Primary symptom is severe diarrhea • Modern treatment involves an IV to provide hydration • Competing Theories for transmission: air vs water (germs). Air was the predominant view.

Golden Square, Sept 1854 Unusually intense, deadly outbreak 500 deaths in just a few days Local panic made neighbors flee John Snow, a physician, believed cholera spread through polluted water supplies

Is this definitive "proof"?

Same picture, but with daily deaths

Aside: quarterly aggregates

Fiscal Year aggregates

Calendar Year aggregate

Water compnies

This area was fed by two water companies

Deathrate less where clean water

Current medical mystery Sudan's Luckless Children, Locked in Land of Nod, NY Times, Sept 22, 2003 Mysterious ailment among some children of Sudan Nod, don't grow fully, die in late teens Theories: fly bite, poison, contaminated food

References found on http://www.ph.ucla.edu/epi/snow.html