Talkback for article: 275, January2003

Demography hands on

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From: Mathieu Roy <yeupou(at)gnu.org> [ date: 2003-01-05 ]
There are several critical issues in this text about definitions and methodology.

I made several comments in French at the following addresses (sorry, no time to translate them)

http://linuxfr.org/comments/162184.html
http://linuxfr.org/comments/162185.html
http://linuxfr.org/comments/162191.html

From: Ralf Wieland <rwieland(at)zalf.de> [ date: 2003-01-07 ]
Dear friends,

here are some remarks for my demography model. I want to make a
simple and easy to understand modell. My intention was not a
scientific application. Therefor are some simplifications in
the model. Firstly the birthrate. I use the mean number of
children per woman. This number is easy to understand and it
can be changed by the user. The program calculates the from
this number the actual birthrate. Please forgive this inaccuracy.
I calculate the birthrate by devision with 30 years (for a
the woman of childbearing age in the program 30 years) That is
a simplification because the propability of childbearing differs
of this period. But this simplification is easy to change by changing
the source code. It can be done in the same way how the migration
is splitted. But in our area of interest in North-East-Germany
this propability is changing very fast over the last ten years and
I had no actual statistical dates. So I only used the simple
variant. For the migration it is not better. We have no statistical
data. So I had to estimate the parameters. But it doesn't matter
in future (if we have better dates) it is easy to adapt the parameters.

You see, I'm a programmer not a demograph. I use models to
understand processes in the nature. Of course we have do to
some work before we can use our modell to forecast the development
in our area. But we have connected our dynamic approach with a
spatial fuzzy model to see how we can estimate the migration as
a function of the space. So we done some calculation to see how
a migration can be in space and in time. So far to the intention of
my work.

The demographic model in the article is only a part of my work.
But I hope it is interesting for someone to play with it. If you
want to do some serious calculations with it you can use the
source code an change it to your conditions. It would be nice
is we could speak about it.

regards

Ralf Wieland

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