[SystemSafety] Qualifying SW as "proven in use" [Measuring Software]

[Steve Tockey]

Martyn,

"It should be no surprise to find that software components that are hard to understand have a higher defect density than those that are easier to understand. One issue, then, is how to measure ease of understanding so that it can be imposed by a standard."

That's what I've been trying to get across all along. The evidence that I have is that three indicators are pretty good measures:
    Cyclomatic complexity
    Depth of (decision) nesting
    Fan out

As I've said, I'm sure there are other relevant indicators as well. What's missing is the correlation analysis that gives us the empirical evidence that the indicators we look at are truly relevant. Both the Lorentz & Kidd and Chidamber & Kemmerer publications (cited earlier) proposed about 20 indicators, but I'm not aware of any serious correlation analysis having been done. I'm sure that most of what's in those publications are irrelevant, but I'm sure a couple of them are relevant. We just need to find a way to get the data and do the analysis.


Regards,

-- steve




From: Martyn Thomas <martyn at thomas-associates.co.uk<mailto:martyn at thomas-associates.co.uk>>
Reply-To: "martyn at thomas-associates.co.uk<mailto:martyn at thomas-associates.co.uk>" <martyn at thomas-associates.co.uk<mailto:martyn at thomas-associates.co.uk>>
Date: Thursday, June 27, 2013 9:30 AM
To: "systemsafety at techfak.uni-bielefeld.de<mailto:systemsafety at techfak.uni-bielefeld.de>" <systemsafety at techfak.uni-bielefeld.de<mailto:systemsafety at techfak.uni-bielefeld.de>>
Subject: Re: [SystemSafety] Qualifying SW as "proven in use" [Measuring Software]

On 27/06/2013 16:10, Steve Tockey wrote:
I would be willing to bet that if the data used in the Hatton study were broken down to the function/method level, a clear correlation would be appear.

It should be no surprise to find that software components that are hard to understand have a higher defect density than those that are easier to understand. One issue, then, is how to measure ease of understanding so that it can be imposed by a standard. Appropriate loop invariants, for example, greatly help understanding, and so do (correct) comments ...

Martyn
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