ECSE-2500, Engineering Probability, Spring 2010, Rensselaer Polytechnic Institute

# Lecture 1

- Why probability is useful
- AT&T installed bandwidth to provide level of iphone service (not all users want to use it simultaneously).
- also web servers, roads, cashiers, ...
- fair price for financial CDO that reduces risk

- Model
- Real thing too expensive, dangerous, time-consuming (aircraft design).
- Capture the relevant, ignore the rest.
- Coin flip: relevant: it's fair? not relevant: copper, tin, zinc, ...
- Validate model if possible.

- Computer simulation model
- For systems to complicated for a simple math equation (i.e., most systems outside school)
- Often a graph of components linked together, e.g., with
- Matlab Simulink
- PSPICE

- many examples, e.g. antilock brake, US economy
- Can do experiments on it.

- Deterministic model
- Resister: V=IR
- Limitations: perhaps not if I=1000000 amps. Why?
- Limitations: perhaps not if I=0.00000000001 amps. Why?

- Probability model
- Roulette wheel: {$p_i=\frac{1}{38} $} (ignoring http://www.amazon.com/Eudaemonic-Pie-Thomas-Bass/dp/0595142362 )