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OK, I haven't done this test, not participated in this debate, but to
get a *real* feel for the statistical standard deviation, you should
calculate it in the percentage change in the close, something like
Stdev(C/Ref(C,-1)-1,30);
You probably need to also annualise this, something like
Stdev(C/Ref(C,-1)-1,30) * Sqrt(250);
using a 250 day year. Note that I use 30 days. To get the standard
deviation to have any validity (or most other indicators for that
matter) you should use 30 or more days. There is a (deep) theoretical
reason for this - I think you can maybe take this number down to 20
but do so at your own risk.
I also *think* that to do any sensible comparison, you have to use the
same number of periods for both. Now, the ATR uses H, L and C, so
*maybe* you can use 10 for the ATR when you use 30 for STDEV, but
maybe not.
Anyhow, looking forward to comments on how this one compares to the ATR.
Regards
MG Ferreira
TsaTsa EOD Programmer and trading model builder
http://www.ferra4models.com
http://fun.ferra4models.com
--- In equismetastock@xxxxxxxxxxxxxxx, "Jose Silva" <josesilva22@xxxx>
wrote:
> Manuel, Andrew, staying away from mathematical jargon if possible,
> let's concentrate on what seems to work best on the markets.
>
> Plot and compare these two indicators below any volatile chart:
>
> ATR(1);
>
> Stdev(C,2);
>
>
> It may be a subtle difference, but I know which one I'd prefer.
>
> And introduce Standard deviation to a large price gap over say, 21
> periods [Stdev(C,21)], and the *increasing volatility* shown by Std
> Dev *after* the event, is simply wrong. Compare to Mov(ATR(1),21,E).
>
> Again, from *my own chart observations*, my view is that the ATR is
> probably the more natural measure of price volatility.
>
> My observations and thoughts may not be mathematically correct, but
> that is the way I view volatility in charts - not as a bunch of
> abstract numbers to be manipulated mathematically, but rather, data
> points representing mass psychology at work.
>
>
> jose '-)
> http://www.metastocktools.com
>
>
>
> --- In equismetastock@xxxxxxxxxxxxxxx, "Manuel Cabedo" <manelcabedo@x
> ...> wrote:
> >
> >> From my own chart observations, I think that the ATR is probably
> >> the best measure of volatility.
> >
> > I don't think so, Jose. Volatility is a kind of dispersion, and the
> > best measure of dispersion is the standard deviation. It is a simple
> > question of statistics. With standard deviation you can do
> > quantitative assertions about the probability of breaking a channel,
> > for instance, or being exited of an operation by a stop.
> >
> > Speaking of securities, I particularly like the standard deviation
> > of daily returns. The distribution of this quantity is not normal,
> > of course, but you can study it on a heuristics base.
> >
> > The work of Bollinger is interesting (I am the translator of his
> > book in Spain) because he always justifies (or tries to.) his
> > methods from a statistical point of view. If someone likes his
> > bands, then reading his book is a must.
> >
> > Once more, thank you, Jose. Your contributions to this forum are
> > always highly valuable (including the one about ATR...).
> >
> >
> > Kind regards.
> >
> > Manuel
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