On 19 Sep 2000, Herman Rubin wrote:
> >No, the probabilities of interest are both those about
> >the observations and those associated with the underlying
> >process.
>
> I would disagree with this in most cases. The probabilities of
> the observations are not likely to give insight, at least in
> many cases. The process is what one makes assumptions about.
Agreed. But there are also many cases where the probabilities
of the observations do give insight. One cannot understand the
double slit experiment in quantum physics without discussing the
distribution of dots on the fluorescent screen which is the
final observable record of the experiment. To understand the
double slit experiment, which is the key to understanding the crucial
concept of wave-particle duality, one requires discussion of both
the underlying process (interference effects in the electron
wavefunction, which is a "probability amplitude") as well as its
observational manifestation (fringes in the distribution of the
dots on the screen). To simply write down the interference
term in the wavefunction gives no physical insight unless the
observational consequences are linked to it.
There are many other examples but I think the point has been made.
> >Alternatively, one could take the view that the continual improvement
> >of models is a means to an end: improved calculations of probabilities
> >of observed events. Science can and has delivered such calculations
> >which have proven tremendously useful, in the form of applications, even
> >to non-scientists.
>
> This is engineering, not science. Science is not much driven
> by it, and this is not adequately realized.
I stand corrected and will rephrase. In engineering, the probabilities
"of interest" include calculations for observable events.
> But the probabilities of interest in applications are not
> likely to be those in the experiments. Those probabilities
> are mainly tools, not items desired per se.
In an application, what is desired is a product with some target
final observational state. Whoever designed the product will use
the theoretical probability model of the underlying process as a means to
accomplish the end. Every time the product is operated, an "experiment"
is performed and the user wants the result of the experiment to match
the prediction promised by the manufacturer. The user may be completely
unaware of the underlying operating principles of the product.
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