TITLE: There Is No Normal
AUTHOR: Eugene Wallingford
DATE: May 03, 2011 4:26 PM
Part of what made
diagnosing my knee injury
challenging is that the injury has not presented normally.
Normally, this condition follows an obvious trauma. I did
not suffer one. Normally, the symptoms include occasional
locking of the joint and occasionally feeling as if the
joint is going to give out. I have not experienced either.
Normally, there is more pain than I seem to be having.
The doctors were surprised by this unusual presentation,
but it didn't worry them much. They are used to the fact
that there is no normal.
The human body is a complex machine, and people subject
their bodies to a complex set of stimuli and conditions.
As a result, the body responds in an unbelievable number
of ways. What we think of as the "normal" path of most
diseases, injuries, and processes is a composite of many
examples. Each symptom or observation has some likelihood
of occurring, but it is common for a particular case to
look quite unusual.
This is something we learn when we study statistical
methods. It's possible that no number in a set is equal
to the average of all the numbers in a set. It's possible
that no member in a set is normal in the sense of sharing
all the features that are common to most members.
A large software system is a complex machine, and people
subject software to a complex set of stimuli and
conditions. As a result, the software responds in a
surprising number of ways. When we think of this from
the perspective people as users, we realize just how
important designing for usability, reliability, and
Programmers are people who interact with software, too,
and we subject our programs to a wide-ranging set of
demands. When we think about "there is no normal" from
this perspective, we better understand why it is so
challenging to debug, extend, and maintain programs.
Our programs may not be as complex as the human body,
and we try to design them rather than let them evolve
unguided. But I think it's still useful to program
with a mindset that there is no normal. That way,
like my doctor, we can handle cases that seem unusual