# error

### Pi: how many digits do you need?

The most basic explanation of Pi is that it is the ratio of the circumference to the diameter for a circle. That seems simple enough, but it turns out that Pi is an irrational number - so you can't just write it down. Oh, I know that you are an uber-geek and you could recite the first 80 digits of Pi. But the question is - how many digits are enough? In this post, I am going to assume that we don't know the true value of Pi (which is essentially true). I can then use propagation of error techniques to see how dependent different calculations are on the value of Pi. Super Brief Intro to…

### RP 9: Error propagation and the distance to the Sun

Some time ago, I wrote about the awesome things the Greeks did in astronomy. Basically they calculated the size of the Earth, distance and size of the moon and distance and size of the sun. The value obtained for the distance to the sun was a bit off, but still a bang up job if you ask me. (where bang-up is meant as a good thing) If the greeks were in my introductory physics lab, they would need to include uncertainties with their measurements. What would the uncertainty in the final value look like? In my introductory physics lab course, I have students measure things and estimate the…

### Errors, publishing, and power

3My piece in yesterday’s New York Times on errors in scientific journals lacked room to consider a key factor generating the sort of fraud that has haunted science lately: The way publishing concentrates and broadcasts not just the sort of error that John Ioannidis writes about, but power and money (its imprimatur), which can corrupt and lead to the sort of fraud Hwang indulged in. While top researchers a couple generations ago lived modestly, today they command fat salaries and wield immense power. These perks provide extra motivation not just for cheating but for the overreaching — the half…