I spent a large part of my professional life in software
testing. There was some hardware testing in there too. At various points
I played the role of statistician, calculating odds: mean time to
failure, earned value, binomial models, markov chains, coverage statistics, mutation
testing, usage models. I even invented methods such as Orthogonal
Problem Calculation (patent pending). During the final decade of my
career my primary role was statistician, although the key role I played
was simply a quality advocate and evangelist — and did I ever preach
from the pulpit.
I suspect most people think the job of a
software tester is to find the bugs before the users. It is true that
finding bugs is a main goal of a tester and that the process of finding
and fixing bugs becomes the myopic focus during the final stages of
development before the “great event,” GENERAL AVAILABILITY! But testing
is a lot more than just finding and fixing the bugs. That was when my
job started.
My focus was always more on error prevention
rather than error detection, and I combed through testing statistics
looking for trends and methods of improvement as well as evidence that
recent process changes and new tools were working as expected. You call
that engeneering “best practices,” and my job was to find and promote the
best practices to encourage efficient and effective, high quality
software development. It was outward focused on the customer and inward
focused on the overall process. I even worked to improve the quality of
the testing itself.
Knowing how to perform distribution
analysis and regressions as well as methods of presenting statistical
results were my day-to-day tasks. I used my teaching skills frequently
as I presented results and recommendations to the workers in the
trenches as well as the captains, colonels, and even the generals and
admirals back at corporate. (You know corporate headquarters; where the
rubber meets the sky.)
Now I spend my time doing a deadly
statistical regression. What are the odds of cancer reoccurrence? Cancer
survivors count the years. That is obvious that you would treasure the
days that are left to you on this terrestrial orb and to celebrate each
additional one like a birthday that had the odds against it. I’m new to
this counting, and I wonder what anniversary you keep track of. You
don’t know when the cancer started. You know when it was discovered and,
in my case, I know when my cancer was surgically removed. We are not
quite to the first anniversary of that event, although it is close —
just a month away.
Doctors are good statisticians.
Mathematical analysis is a major part of their profession as researchers
determine the efficacy of treatment methods. Methods of medical
experimentation are very refined and most medical news we hear in the
press is based on the results of some study or statistical survey. They
even do studies of the studies, something called a combined study.
When
I was first diagnosed, I dug deep into the cancer literature and found
many, very technical and intense statistical expositions. One key was a
classification of a cancer by its stage. At the time the doctors thought
my cancer was stage one, which is where you want to be, even though it
may be sort of like a “little bit” pregnant. It was after my surgery and
the biopsy of the tissue removed that I got the bad news: my cancer had
spread and I was elevated to stage three cancer. Now there is worse
news, stage four, but it was not my goal to score the highest on this
particular exam.
So, I went to the literature. Stages can
be used to calculate your life expectancy. All the tables use stage as a
parameter in calculating longevity. The math is based on stage to
predict the probability of the number of years of no reoccurrence of
cancer — doesn’t that have a positive ring: YEARS of no reoccurrence.
That means both that the cancer has not returned, at least not yet; but
it also means additional birthdays. That’s the secret to long life, you
know, it has been proven in study after study that people that have the
most birthdays live the longest. That’s my goal.
So here
is what the tables and charts tell me. In my case, if there is no
reoccurrence of cancer after three years, then only 70% of the stage
three prostate cancer patients have a reoccurrence. If you can make five
years without a reoccurrence, then the odds improve to 50%. Now I’m
not a gambler and don’t go to Vegas for my vacations, but I got to say
that those are pretty long odds. Don't get too discouraged, even if the
prostate cancer reoccurs there are additional treatments such as
radiation and hormonal treatment. That guy that Scotland released from
prison for the Lockerbie bombing lasted years beyond what the doctors
had predicted. As they say, “it is hard to make predictions, especially
about the future.”
Also skewing the stats is the fact that
prostate cancer is a disease of old age, and plenty of victims die of
other causes before the cancer can get them. Prostate cancer is
typically a slow growing malignancy, so that further improves the odds,
although in my case there are concerns I have a rare, fast growing
version. Wouldn’t you know it, the statistician suffers from a black
swan (look it up on Wiki — the theory, not the movie).
So
I’m tracking the numbers and making the graphs. Two more anniversaries
and my odds of no reoccurrence jump up to 30%. Those are slim odds, but I
don’t spend a lot of time worrying about it. I think the best defense
is to live, love, and laugh. No-one knows the future, and people beat
the odds all the time. I often feel like the guy with no shoes, when all
around me are people with no feet. I originally wrote about cancer in
the context of four men that I knew — I was the fourth. Two of them had
died shortly after the discovery of cancer and two of them — again I
was one of those two — still survived. Well, my dear friend ‘F’
succumbed last month (and I sure miss him). So it is now down to me.
That’s 25% for those calculating. I don’t suggest you graph it with
years as the abscissa. It is not a happy graph. No, I prefer the
“bathtub curve.” After all, it makes a “smiley face.”
I
think the foggy and dreary day led me to these musings. Please don’t
worry about me. The last thing in the world I am is depressed. Just the
opposite. Life has been a continued shower of blessings on this humble
traveler, and I will go to my maker with the same smile I wore when I
walked into the conference room with a stack of statistics under my arms
and a message about quality in my heart.
Originally written Sept. 6, 2011.
Sunday, September 16, 2012
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