[gclist] Name that hypothesis

Nick Barnes nickb@harlequin.co.uk
Thu, 05 Dec 1996 11:09:23 +0000


> > > "A young object is more likely to die soon than an old one".
>
> [...]
> 
> I think you misunderstood me, which bodes ill for my phrasing of the
> hypothesis.
> 
> I tried to carefully word my statement so that it meant: "an object
> randomly selected from the set of young objects has a higher
> probability of dying in a given time interval than an object randomly
> selected from the set of old objects", which is the hypothesis that we
> want.
> 
> You seem to be interpreting my statement as "an object randomly
> selected from the set of objects which will die in a given time
> interval is more likely to be a young object than an old object". This
> is broken for exactly the reason you point out in your paper.

That is, I mean

P(die | young) > P(die | old)

	not

P(young | die) > P(old | die)

A more precise statement is that the instantaneous half-life increases
monotonically with age.

Nick B