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[amibroker] Re: Ehlers Modified Optimal Elliptal filter



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"kut2k2" <kut2k2@xxxx> wrote:
"The problem here is that sometimes you *want* significant lag."

Pfff.... Only a non-trader would come up with such a ridiculous 
statement.  Any amount of trading lag in the markets is absolutely 
deadly.


".. the key is to find the best data-adaptive smoothing factor 
possible."

No amount of adaptive smoothing is going to compensate for the fact 
that a lagging indicator is based on two-dimensional historical data, 
meaning it fails to consider the bigger picture - major market 
influences.  Price action is generally composed of only 30% local 
influences, and at least another 30% of major market influences - the 
rest being market noise.

If one's aim is a successful trading career, the key is actually to 
think outside the square and concentrate on doing something different 
from the other 90% of traders.  Don't waste time with trying to build 
a better mouse trap, if you want to win the rat race.


jose '-)



--- In amibroker@xxxxxxxxxxxxxxx, "kut2k2" <kut2k2@xxxx> wrote:
> 
> --- In amibroker@xxxxxxxxxxxxxxx, "Corey Saxe" <res1wgwl@xxxx> 
wrote:
> > From Stocks & Commodities V. 18:7 (July 2000) (pp. 20-29): Optimal 
> Detrending by John F. Ehlers
> > 
> > modified optimum elliptic filter in TradeStation EasyLanguage:
> > Smooth = 0.13785*(2*Price - Price[1]) + 0.0007*(2*Price[1] -
> > Price[2]) + 0.13785*(2*Price[2] -Price[3]) + 1.2103*Smooth[1] -
> > 0.4867*Smooth[2]
> > 
> > Or, algebraically:
> > 
> > Smooth = 0.13785 (2 x Price - Price[t-1]) + 0.0007 (2 x Price[t-1] 
> > - Price[t-2]) + 0.13785 (2 x Price[t-2] - Price[t-3]) + 1.2103
> > 
> > (Smooth[t-1] - 0.4867 x Smooth[t-2])
> > 
> > where Price=(High+Low)/2
> > 
> > 
> > 
> > -CS
> > 
> > ----- Original Message ----- 
> > 
> >   From: raven4ns 
> >   To: amibroker@xxxxxxxxxxxxxxx 
> >   Sent: Saturday, October 23, 2004 7:58 AM
> >   Subject: [amibroker] re:Ehlers Modified Optimal Elliptal filter
> > 
> > 
> > 
> >   Hello,
> >   Does anyone know where I might find this filter? I was looking
> >   at the new Jurik MA and this certainly looked like a reasonable 
> >   substitute. Thank you.
> > 
> >   Tim
> 
> I'm not convinced this filter is all that "optimal".  According to 
> Ehlers:
> 
> "... I have been curious about how to design an optimum smoothing 
> filter.  I set one criterion to be that the smoother could have no 
> more than a one bar lag.  An elliptic filter provides the maximum 
> amount of smoothing under the constraint of a given lag.  So, using 
> MATLAB, I designed an elliptic filter ..."
> 
> The problem here is that sometimes you *want* significant lag.  
Here's 
> the sitch: most filters affect both signal and noise. Filtering 
noise 
> is good: that's what you want to get rid of. But filtering signal is 
> bad: that's where lag and attenuation comes from.  So in areas of 
low 
> signal-to-noise ratio, you want a lot of filtering, and in areas of 
> high SNR, you want little or no filtering. The only way to 
accomplish 
> this for non-stationary, non-linear time series like financial data 
is 
> with an adaptive moving average. Most AMAs are basically variable 
> EMAs, but Jurik denies this is what his AMA is. Maybe so. For the 
rest 
> of us "home-brewers", the key is to find the best data-adaptive 
> smoothing factor possible.
> 
> Good trading,
> kut2k2





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