[SystemSafety] Post Office Horizon System

Derek M Jones derek at knosof.co.uk
Mon Jan 4 16:45:09 CET 2021


Peter,

> Yes the Post Office case was a scandal.

Yes it was, and has yet to be fully rectified.

> The PO used some very dodgy statistical arguments to support their
> reliability claim
> - rebutted in:
> 
> https://ials.blogs.sas.ac.uk/2019/06/26/the-use-of-statistics-and-software-code/

The statistical arguments made by both side in this case were very
dodgy.

The arguments were variations on the theme of there being 1 in 14 million
chance of winning the UK lottery, therefore it is unlikely that anybody will
win it; ignoring the fact that as more people play the chance
of somebody winning increases.

In the Horizon case there was insufficient data available to estimate the
probability of a fault being experienced.

-- 
Derek M. Jones           Evidence-based software engineering
tel: +44 (0)1252 520667  blog:shape-of-code.coding-guidelines.com


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