GoM Lamellibrachia

Geoff Read g.read at niwa.cri.nz
Fri Feb 11 04:55:20 EST 2000


Stephane wrote:

> younger worms grow over 10 cm per year but 
> the bigger ones grow only less than a cm per year. It is based on this 
> non-linear relationship that the lowest estimate of 80 years was obtained. 

That's probably what they meant to say - maximum likely growth at each 
length X. They actually say "Even if it were assumed that individuals 
could maintain their maximum growth rate [the growth of smaller worms] 
THROUGHOUT THEIR LIVES, the larger animals would still be over 80 
years old."  Note that there are several individuals in the around 100 cm 
size with growth rates up to double the "theoretical maximum growth rate" 
curve.

> 	This is a very serious work, statistically robust. 

Really? I see no sample number, no raw data, no error estimates (I think 
they would be enormous), no parameters for the equation, and a scatter 
plot that looks like it will have abysmal predictive power. Is this a random 
sample of the population, not biased towards older, or at least larger, 
individuals? Does it show age classes? I want  the size histogram so 
these things can be judged.

A model equation that is the "best and most robust fit" simple means it 
was the best of those tried. I need to know in what way was it robust? 
Some statistical test perhaps? Evidence please. 

Our growth is also non-linear so I am imagining estimating maximum 
human longevity through the same concept. How accurate do you think 
the result would be?  


--
   Geoff Read <gread at actrix.gen.nz>


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