# how to estimate anything

Post on 13-Feb-2017

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## Data & Analytics

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• HOW TO ESTIMATE ANYTHINGLearning Night - 01/21/15

• WHAT IM TALKING ABOUT TODAY What is a Fermi Estimation?

An example to get us going

Some tips and tricks

Try it yourself!

Skeptical?

• EVER WONDER HOW MANY OR HOW OFTEN SOMETHING HAPPENS?

• HOW MANY PIANO TUNERS ARE IN SAN FRANCISCO?

• PIANO TUNERS 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

• 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!

• USEFUL FOR

Interviews!

Satisfying personal curiosity

Trying to figure out whether or not Maroon 5 really crashed all those weddings

• TACTICS

Top down vs. Bottoms up

Give a range!

Easy numbers = Good numbers

Key is make assumptions based on what you know

• HOW MANY PEOPLE ARE NAMED JONATHAN IN THE WORLD?

• 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

• SKEPTICAL?

Fermi is for

quick estimates

magnitude

starting points

• "FERMI ESTIMATES WORK BECAUSE THE ESTIMATIONS OF THE INDIVIDUAL TERMS ARE OFTEN CLOSE TO

CORRECT, AND OVERESTIMATES AND UNDERESTIMATES HELP CANCEL EACH OTHER OUT. "

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