Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!uakari.primate.wisc.edu!brutus.cs.uiuc.edu!psuvax1!psuvm!uh2
From: UH2@PSUVM.BITNET (Lee Sailer)
Newsgroups: comp.sw.components
Subject: Re: Schedule and budget are secondary
Message-ID: <89286.104355UH2@PSUVM.BITNET>
Date: 13 Oct 89 14:43:55 GMT
References: <16168@vail.ICO.ISC.COM> <6693@hubcap.clemson.edu>
Organization: Penn State University
Lines: 74

<16187@vail.ICO.ISC.COM> <1189@mrsvr.UUCP>

In article <1189@mrsvr.UUCP>, hallett@positron.uucp (Jeff Hallett x5163 ) says:
>How   does  one  specify  a  requirement   for "user  friendliness" or
>"well-written"?
>

I know many will scoff, but you can measure these things.  Just go ask a
social scientist, eg psychology, sociology, anthropology.  These guys
measure such fuzzy things all the time.  So, without further ado, here's
a brief course in Measurement:

What is a meausre?

We have some concept from the world, like 'user friendly'.  The domain is
the set of all programs we are concerned with.  We'd need a function that
maps from the domain to something arithmetical, say the set of reals.
That function is a measure if some features of arithmetic on the
resulting reals behave in a way that reflects the behavior of the objects
in the domain.

Consturcting that function is the art of measurement.

Example--User Friendliness

Let's use a spreadsheet as an example.  Prepare a test, say 8 or 10 problems
that spreadheet users should be able to solve.  To measure the user friend-
liness of spreadsheet X, choose 100 typical users at random, give them
some fixed amount of instruction, say 5 hours, and then give them the test.
The average score of those 100 users on the test is a number,  UF(X).

Repeat for spreadsheet Y with a new group of 100 users.  This produces a
number UF(Y).

In fact, for any spreadsheet Z there is in theory at least a number UF(Z),
so UF: Spreadsheets ------> reals is (within some variability from group
to group) a function.  I contend that if UF(X) > UF(Y) then spreadsheet
X is more user friendly than Y is, which makes UF an "ordinal" measure.

Comments

That's pretty expensive, isn't it?  Yes, it is.  Some things are easy to
measure.  The physical scientists snapped those up pretty early, eg
length, weight, temperature, strength.  Some things are hard, eg
time, space, subatomic thingies, and nearly all the stuff social
scientists are studk with.

Do UF(x)-UF(y) or UF(x)/UF(y) mean anything?  These arithmetic operations
may not be used on our example measure, UF.  However, techniques for
creating scales where these operations may be used are available, eg
Magnitude Scaling.

Where can I learn more?  The library, or course, is full of books.
Start with Research Methods in _______________, where the blank is
any social science.

Measuring "well-written"

Give the code to the quality control team.  They study the code, and then
introduce bugs on purpose.  Give the code to another team that debugs it.
This produces several numbers:  the number of introduced bugs they find,
the number of introduced bugs they correctly fix, the number of new
bugs they find.  high scores for the first two indicate well-written
code, and high numbers for the second indicate poorly written code.
That's three measures.  You might stick them together with something
like
     WW =  (measure1 + measure1)/measure3


Is this fuzzy and squishy?  Yes, of course it is.  More money poured on
the process would make the measurement more precise, valid, reliable, and
so on, but may not be worth it.

lee