SOFTWARE QUALITY CONCEPTS - Software Design for Six-Sigma: A Roadmap for Excellence - page 17

Are complex structures used in the code? (C7)
Does the detailed design contain clear pseudo-code? (D7)
Is the pseudo-code at a higher level of abstraction than the code? (P7)
If tasking is used in concurrent designs, are schemes available for providing adequate test
cases? (T7)

The membership function for measuring the software quality with respect to
testability can be defined as follows:

µ Testability = f7(C7 , D7 , P7 , T7)

1.7.8 Usability

Usability of a software product is the convenience and practicality of using the
product. The easier it is to use the software product, the more usable the product is.
The component of the software that influence this attribute the most is the graphical
user interface (GUI). 8 A sample of questions that can be used to measure the software
usability:

Is a GUI used? (G8)
Is there adequate on-line help? (H8)
Is a user manual provided? (M8)
Are meaningful error messages provided? (E8)

The membership function for measuring the software quality with respect to
usability can be defined as follows:

µ Usability = f 8(G8 , H8 , M8 , E8)

1.7.9 Reliability

Reliability of a software product is the ability to perform its intended functions within
a particular environment over a period of time satisfactorily. A sample of questions
that can be used to measure the software reliability:

Are loop indexes range-tested? (L9)
Is input data checked for range errors? (I9)
Is divide-by-zero avoided? (D9)
Is exception handling provided? (E9)

8 http://en.wikipedia.org/wiki/Software quality.