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

From: Steve Tockey < >
Date: Sat, 2 Apr 2016 18:39:36 +0000

Of course, I agree 100%.

What's your source for the 44% number? I'm very interested in that kind of data. My source says 56% of defects are in requirements and 27% are in design. Only 7% are coding. The remaining 10% are defects logged against other things: test cases, test plans, project plans, etc.

The source of this data is:

Gary Mogyorodi, ³What is Requirements-Based Testing?², Crosstalk, March, 2003

-----Original Message-----
Date: Saturday, April 2, 2016 12:10 AM
To: Steve Tockey <Steve.Tockey_at_xxxxxx Cc: "systemsafety_at_xxxxxx <systemsafety_at_xxxxxx Subject: Re: [SystemSafety] Data on Proof effectiveness from real projects

On 02/04/2016 at 6:38 AM, "Steve Tockey" <Steve.Tockey_at_xxxxxx
>Bev wrote:
>"This is indeed interesting. But what was the the definition of
>³efficiency of fault detection² here? Finding the most faults for
>a given outlay of effort? Maximising the chance of finding all
>faults? I can imagine other definitions."
>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.

When the largest proportion (44%) of the defects occur within the specification phase it should be obvious where defect removal should be most concentrated.


Paul E. Bennett IEng MIET
Systems Engineer

Paul E. Bennett IEng MIET.....<email://Paul_E.Bennett_at_xxxxxx
Forth based HIDECS Consultancy.............<>
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