[SystemSafety] Software reliability (or whatever you would prefer to call it)

[Derek M Jones]

Martyn,

> The company calculates some measure of the amount of usage before
> failure. Call it MTBF.

Amount of usage for a given input distribution.

A complete reliability model has to include information
on the software's input distribution.

There is a growing body of empirical work that builds
fault models based on reported faults over time.  Nearly
all of them suffer from the flaw of ignoring the input
distribution (they also tend to ignore the fact that
the software is changing over time, but that is another
story).

-- 
Derek M. Jones           Software analysis
tel: +44 (0)1252 520667  blog:shape-of-code.coding-guidelines.com