On Wed, 13 Aug 1997, Glenn Johansson wrote:

> >Would you ever quote this formula to the parent of a child killed in
> >a plane crash - Eh ?
>
> How does a person in power decide how much money to set aside for
> improved fire safety that could save lifes and equipment in a fire, how
> much money to set aside for additional robbery prevention that could
> save lifes and money in the event of a robbery, and how much money to
> set aside for non-safety related things like marketing campaigns, etc?


I think the point of the original poster was that brain power, common
sense, and engineering principals should be used to determine if there is
a realistic potential of harm to a user.

The whole idea of attaching a formula to safety or threat is just a
feel-good measurement.  The number you calculate is only a
guideline, nothing more.

An analogy: There are plenty of books and academic studies on reliability.
Calculations can be done on MTBF and so forth, but there's more to
reliabilty than just numbers.  Assesing criticality and providing
redundancy are part of the process, as well as making sure parts come
from reliable vendors and manufacturing of product is done in a careful
manner.  I can sit and apply a calculation of MTBF on a box of parts, but
if they aren't designed properly or manufactured well, it doesn't mean
much.

> it that you as a person in power would base your decisions on? Is it
> media campaigns, saying "cute kid drowned in deep black well - now we
> must rebuild all wells and make them safer so it never happens again",
> or a calculation (using a scientific risk analysis concept) of which
> safety measures can save more lives?


As with this hole risk assesment thing, there is no calculation that can
determine the number of lives saved by doing certain things.  A
calculation is only a guideline.

> >In the context of the clock radio how do you decide from the number you
> >get from your 'formula' whether you should make a mental note about its
> >contstruction - as this might be useful when filling in an insurance
> >application - Eh ?
>
> If you think it is going to take 15 minutes to analyze the fire safety
> of a clock radio, it is going to mean it costs you 12.50 dollars if your
> salary is 50 dollars per hour. (If it's your spare time, your time is
> still about as valuable - slightly LESS if you really wanted to work
> longer than what you do, and slightly MORE if you really wanted to work
> fewer hours per day). If the estimtated probability that what you will
> learn from the investigation of the clock radio is about 5% that it is
> built in a way you appreciate it is 2% likely to cause a fire, which
> will cause predicted damages of an average 2000 dollars, then the threat
> has a value of 2 dollars (0.02*0.05*2000), which means you overreacted
> by 625% (12.5 / 2) on this threat.


I could look at it another way.  By spending 12.50 and saving 2000 in
damages, I have saved a lot of money.  2000-12.50 = 1987.5.  But the 2000
number is hypothetical.  The fire could cause enough damage to just
destroy the clock, OR burn down a house and kill a family.  A lot of
variation in that Harm portion of the equation.  What Harm # would you
apply in this case?

>
> Glenn
> Sweden
>

I don't mean to jump on anybody's back about this.  I just felt i wanted
to give my humble opinion :)

Rob