![HERO OF OUR STORY
– JOHN SNOW
• If you lived in the north of London
• The chances of dying was much lower
• (26/10000)
• But if one lived in the north of london,
• the chances of dying was much higher
• (80/10000)
[They] furnish no proof of the
Correctness of his views –
London Medical gazette](https://image.slidesharecdn.com/datasciencemeetupnagarro-171212115833/85/Looking-at-Data-4-320.jpg)
Looking at Data
- 1. DATA – DO WE LOOK AT IT?
- 2. THE LONDON EPIDEMIC A motivation
- 3. STORY BEGINS 1605 225,000 1801 1 million 1851 2.3 million 5 people / room 420/per acre This was the area of London where the cholera outbreak happened Did not have a decent sewage system Vibrio cholera 1831-first case of cholera in britain 1832-1833- 20,000 dead 1840s – 50,000 dead In the 1850s there was no Germ Theory then. People believed that diseases were carried by bad air – “miasma theory” (bad smell was a strong indicator of germs and hence disease)
- 4. HERO OF OUR STORY – JOHN SNOW • If you lived in the north of London • The chances of dying was much lower • (26/10000) • But if one lived in the north of london, • the chances of dying was much higher • (80/10000) [They] furnish no proof of the Correctness of his views – London Medical gazette
- 5. THE SUGGESTED EXPERIMENT The experimentum crucis would be that the water conveyed to a distant locality… produces the disease in all who used it while those who do not use it, escape London Medical Gazzette (1849)
- 6. 5 YEARS LATER THIS EXACT EXPERIMENTED HAPPENED - 1854 On Aug 28th 1854, Francis Lewis a 5 year old girl contracted cholera , and while waiting for the doctor, her mother washed her diaper and threw away, the dirty water into a cess pit outside the door on 40th Broadstreet. This cess pit was extremely close to a very popular well. The cess pit was not properly maintained and it contaminated the well. 3 days later 100s of people in the neighborhood became sick. In the next 2 days 300 people died in that neighborhood.. John Snow jumped on this instance on the 5th day….
- 7. THE EXPERIMENTER He lived 10 blocks away and so he went and drew water from that well and along with it 4 other wells in the neighborhood… His microscope was not powerful enough to reveal bacteria in that water.. He walked to the ‘Registrar of Deaths’ and asked for the partial results for that week and he plotted it..
- 9. HIS ANALYSIS
- 10. COMPELING – BUT STILL NOT GOOD ENOUGH TO RULE OUT MIASMA THEORY He walked around and started interviewing people both from houses, where people had died and places where people did not die. There was a neighborhood where only 3 children had died and they had gone to the same school in a different neighborhood and the school water Supply was contaminated. There was a brewery where no one had died and their water supply was from a different source and they were drinking a lot more beer (the staff was allowed to drink a little) than they had water. There was a woman who had lived on Broad street for all her married life and she had developed a taste for the water from that pump. After her husband died, she had moved away to another neighborhood and her sons had arranged for getting her bottled water from that pump everyday. She had died 4 days after the Broadway pump had gotten infected. And no one from her neighborhood had died.
- 11. CONFIRMATION If Miasma theory was correct how could air choose ’which buildings’ to infect.
- 12. ACTION AND VICTORY Based on this evidence the pump handle from the Broadstreet Pump was *reluctantly* removed and the water source closed. And almost single handedly armed with his ability to dive into the details of data, that he painfully collected, John Snow saved many many people…
- 13. CONCLUSION 1. Look at the high level information in your data 2. Look at how your data is distributed 3. Dive into the details of your interesting observations.