Re: [SystemSafety] Data on Proof effectiveness from real projects

From: Littlewood, Bev < >
Date: Sat, 2 Apr 2016 15:17:26 +0000

On 2 Apr 2016, at 16:02, Martyn Thomas <martyn_at_xxxxxx

On 02/04/2016 06:37, Steve Tockey wrote: Generally speaking, efficiency is looking at investment per unit of work done. In other words, increasing efficiency means that the same work is done at lower investment—the same (number of?) defects are found for a lower investment. Maximizing the chance of finding defects would be an issue of effectiveness. Effectiveness is looking at the rate at which the job is done correctly (I.e., a defect is found, not missed). One needs to look at both efficiency and effectiveness of processes to make a fair comparison.

Is anyone actually interested in the number of defects found? Surely that's not a measure of anything useful about the software.

Exactly! That was what my post of a couple of days ago was about (although I’m not sure it went to the list). I suggested that not all defects are born equal w.r.t. their impact on unreliability.

An important benefit of verification is that it can tell you (for some classes of defect) that the number of defects remaining is zero.

Or at least high confidence that it is zero…

Bev

Martyn



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Bev Littlewood
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systemsafety_at_xxxxxx Received on Sat Apr 02 2016 - 17:17:42 CEST

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