Joel on Software

How it works

Record feature points in cards

Estimate how long the card will take to complete

Record how long it actually took to complete

Create a model of how far off the reality is to estimate with respect to the estimator

Use the model to simulate completion of future tasks; ex. in 100 futures, sample from the model, compute how many futures you meet the deadline.

Estimated work hours will then have to be run through calendars, to account for ex. 10 work hours may end up being two calendar days.

Timesheets

It is OK to keep the clock running during interruptions. The estimates will come to include distractions and setbacks and predicted schedules will still approximate accuracy.