Re: System Measurability LO3390

Beth Clark (eclark@atqm.advtech.uswest.com)
23 Oct 1995 17:22:01 -0600

Reply to: RE>>System Measurability LO3375

Michael Ayers wrote:

"So doesn't any measure of quality depend on someone's value scheme? And
doesn't the 'ladder of inference' (5th Disc Fldbk, p245) remind us that
that the value scheme affects what we observe? "

In the case of information technology systems, I believe you want the
value scheme to affect the measures of quality. You want to instill in
the engineering culture the belief that IT solutions are built and
operated to satisfy business needs and that there are performance measures
that indicate how well a system satisfies those needs. If you know what
you're trying to build, the systems measures needn't be entirely
subjective (although some always will be).

Systems engineers use the concept of "technical performance measures" when
evaluating a design, with the ultimate criterion usually being
cost-effectiveness. Cost effectiveness is the measure of a system in
terms of how well it satisfies the 'mission' is was implemented for and
total life-cycle cost. I submit that your IT team should also be able to
put requirements and measures around considerations like

the functional design - the technical and physical characteristics that
the system when operating must exhibit to accomplish its planned
'mission'.

reliability - the characteristic of a design/implementation concerned with
the successful operation of a system.

maintainability - the characteristic of a design/implementation concerned
with the ease, economy, safety, and accuracy of maintenance functions.

manability or human factors - the characteristic of a
design/implementation concerned with the interaction between people and
the computer system.

supportability - the characteristic of a design/implementation concerned
with ensuring the system can be supported effectively and efficiently
throughout its planned lifecycle.

economic feasibility - the characteristic of a design/implementation
concerned with maximizing the benefits and cost-effectiveness of the
overall system throughout its lifecycle.

social acceptability - the characteristic of a design/implementation
concerned with ensuring that the system can become an acceptable part of
the social system.

--
Beth Clark
U S WEST Communications
Information Technologies 
eclark@advtech.uswest.com