How to Estimate Anything
- 1. HOWTO ESTIMATE ANYTHING Learning Night - 01/21/15
- 2. WHAT I’MTALKING ABOUTTODAY • What is a Fermi Estimation? • An example to get us going… • Some tips and tricks • Try it yourself! • Skeptical?
- 3. EVER WONDER HOW MANY OR HOW OFTEN SOMETHING HAPPENS?
- 4. HOW MANY PIANOTUNERS ARE IN SAN FRANCISCO?
- 5. PIANOTUNERS IN SF • 1M people in SF • 2 people per household • 1/20 households have a piano • each piano tuned once a year • 2 hours to tune a piano • tuners work full time for 40 hours a week
- 6. THE MATH • 1M people / 2 people per household = 500K households • 500K * 1 / 20 pianos/household = 25 000 pianos = 25 000 piano tunings per year • 1 hour to tune a piano = 100 000 piano tuning hours • 100 000 hours / 2 000 hours per piano tuner = ~50 piano tuners!
- 8. USEFUL FOR… • Interviews! • Satisfying personal curiosity • Trying to figure out whether or not Maroon 5 really crashed all those weddings…
- 9. TACTICS • Top down vs. Bottoms up • Give a range! • Easy numbers = Good numbers • Key is make assumptions based on what you know
- 10. HOW MANY PEOPLE ARE NAMED JONATHAN INTHE WORLD?
- 11. LOL.WHAT A DOUCHE. • Jonathan is a Male name • 50% of population is Male • Only Westernized civilizations will name kids Jonathan (2B people) • 1/16 Males named some variation of Jonathan (Jon, John, Johnathan etc) • 3B * 50% * 1/16 = 62.5M people named Jonathan
- 12. SKEPTICAL? • Fermi is for… • quick estimates • magnitude • starting points
- 13. "FERMI ESTIMATES WORK BECAUSETHE ESTIMATIONS OFTHE INDIVIDUAL TERMS ARE OFTEN CLOSE TO CORRECT, AND OVERESTIMATES AND UNDERESTIMATES HELP CANCEL EACH OTHER OUT. "