Vipera berus population densities

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Re: Vipera berus population densities

Postby Jeroen Speybroeck » Mon Oct 15, 2012 7:00 pm

Berislav Horvatic wrote:since the result is not a set of estimates. In short, "a measure of deviance to
EACH n°/ha", which you asked for, does not exist

Well, sorry, Bero, but as far as I know (which is not much, I admit...), this is not true, or at least renders the calculated population size estimate weak.
To me, it's also a basic scientific principle - all estimates require some indication of confidence.

Berislav Horvatic wrote:(= is not given by the procedures).

Thus, not "=", imho.

Berislav Horvatic wrote:Using several methods gives several different estimates, which can then be compared among themselves,
to get the feeling how much they differ.

If each estimate is associated with a huge variance, it is irrelevant whether they produce similar population size estimations or not. In contrast, similar estimates with dissimilar variances CAN be indicative for preferring a method.

Berislav Horvatic wrote:But it makes no sense to calculate the average value of these
results and the corresponding SE

Of course not. The variance to a population size estimation is not really the same as the statistical variance formula.
http://en.wikipedia.org/wiki/Mark_and_recapture

Berislav Horvatic wrote:(Anyhow, that's NOT what you asked for.)

Euh... Indeed.

I rest my case.
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Re: Vipera berus population densities

Postby Berislav Horvatic » Mon Oct 15, 2012 9:15 pm

If each estimate is associated with a huge variance, it is irrelevant whether they produce similar population size estimations or not.

Of course, IF the particular method/procedure producing the estimate does give the "variance" ( of what?) at all. I've been told that it does not, TECHNICALLY. (Just quoting the people who did it... and so should know what's obtainable, and what isn't.)

In contrast, similar estimates with dissimilar variances CAN be indicative for preferring a method.

Of course, but only IF they produce any variances of their own (to be compared consequently). I've been told that they do not.
(See above.)
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Re: Vipera berus population densities

Postby Jeroen Speybroeck » Tue Oct 16, 2012 7:13 am

Berislav Horvatic wrote:I've been told that they do not.

I know that by now, I just don't buy it.
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Re: Vipera berus population densities

Postby Berislav Horvatic » Thu Oct 18, 2012 3:34 pm

Jeroen Speybroeck wrote:
Berislav Horvatic wrote:I've been told that they do not.

I know that by now, I just don't buy it.

In the meantime I had a look into these things myself (that is, without asking/believing the "users"),
and I have come to agree with you...
Now I don't see why people don't give the variances, if they are obtainable...
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Re: Vipera berus population densities

Postby Jeroen Speybroeck » Thu Oct 18, 2012 3:51 pm

Berislav Horvatic wrote:
Jeroen Speybroeck wrote:
Berislav Horvatic wrote:I've been told that they do not.

I know that by now, I just don't buy it.

In the meantime I had a look into these things myself (that is, without asking/believing the "users"),
and I have come to agree with you...
Now I don't see why people don't give the variances, if they are obtainable...


Aha... I knew you are a man of reason. ;)
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Re: Vipera berus population densities

Postby Berislav Horvatic » Thu Oct 18, 2012 4:00 pm

But I still find it hard to believe that all these researchers would REFUSE to give
the variances for the shameful reason that they might be EMBARRASSING...
I'd rather believe that they don't know how to get them, or just don't bother to.
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Re: Vipera berus population densities

Postby Jeroen Speybroeck » Thu Oct 18, 2012 4:30 pm

Berislav Horvatic wrote:But I still find it hard to believe that all these researchers would REFUSE to give
the variances for the shameful reason that they might be EMBARRASSING...
I'd rather believe that they don't know how to get them, or just don't bother to.

Agreed. Some day, we'll be friends. ;)
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