Bollinger Bands

Got to admit I have a soft spot for them, here's a 1 min Scalp chart with 6 period Triangular moving average with +2 offset

<IMG src=http://i9.tinypic.com/4cndxrq.jpg width=800>
 
Quote from Spxdes:

Nice chart Trader28Lite!

What is the triangular ma? Is it a T3ma? Thanks.
Triangular is very similar to a simple moving average, just a slightly better curve, but almost identical if you don't have it
 
How does the offset work? That is (I guess) what bars are used to compute the triangular MA whose value is used to detect the crossover with the BB MA? (For my edification, formulas and parameter values would help me understand what is going on.) (Like the chart!) My thanks in advance.

-Pete
 
Quote from phg:

How does the offset work? That is (I guess) what bars are used to compute the triangular MA whose value is used to detect the crossover with the BB MA? (For my edification, formulas and parameter values would help me understand what is going on.) (Like the chart!) My thanks in advance.

-Pete

Most charting software allows you to offset a moving average. All this means is that you can horizontally shift it to the left or right, whichever you prefer.

They are called displaced moving averages by the way.
 
Quote from hypostomus:

Whitster. I was deadly serious. I have spent many a dark night attempting to devise a volatility-based reversal indicator. Perversely (or perreversally), every one I tested was better if recast as a continuation indicator. Big runs draw old ladies away from their knitting and attract mischievous cats to unattended keyboards.

Obvious entry cats always react to red light. as seen when the price gapped up at the open on 026-07 and went outside the upper band.

Akuma
 
Thank you very much Pro_Trader for that interesting distribution chart. If both positive and negative values were plotted the distribution, i'm guessing, would look more Lorentsian than Guassian. But very interesting, and surprising at the same time.

To Rhino: I'm not sure what you are driving at since we are both saying the same thing, although i'm not sure your statement regarding 50/50 probability of moving higher or lower is correct for prices away from the mean. I'll have to think about that. I was referring to what would be true on average, of course, and not what would be true for any one sample, about which nothing could be said ahead of time. In other words, if the data was distributed normally, and one knew the true standard deviation, then 5% of the price samples would indeed lie, on average, beyond plus and minus 1.96 standard deviations from the mean. I guess you were bothered by my using the word "moving". My main point was that prices of individual stocks are probably not distributed normally about the mean so that one should not state probability figures that one often sees incorrectly applied to Bollinger bands. In a nutshell, that's all i'm saying.
 
Quote from piezoe:

(It is Sat. night, it is cold and rainy, and generally miserable outside, so rather than watch George Foreman demostrate his new weenie cooker i decided to haunt these forums.)

I want to throw in a little comment here regarding the interpretation of Bollinger's bands. It is often said that when prices stray two standard deviations from their mean, that "there is a only a five percent chance of the price moving further away from the mean." Or other equivalent and equally incorrect statements. Bollinger, himself, to my knowledge, never made such an error of interpretation. I read his book ages ago.

That business of assigning probabilities comes straight out of statistics for a normally distributed population with a fixed and known population standard deviation. In that case, it is true that 95% of observations that might be drawn from the population would fall, on average, between plus or minus 1.96 standard deviations of the population mean.

But i have never seen any data that would suggest that individual stock prices observed for finite periods are normally distributed about the mean. anyone in this forum have any idea what the distribution function of prices about the mean actually looks like? I would be most curious to know, and of course delighted if the distribution actually did obey Gauss's function. Surely there are some Ph.D. physicists toiling late into the night for Goldman that could shed light on this issue. Or perhaps one of you guys with access to raw time and price data will plot the actual distribution out so we can see what it looks like.

In the meantime, we ought not to attribute specific % probabilites to price interceptions of the bands. Not anyway until we hear definitively from the physicists. There is nothing at all wrong with calculation of the standard deviation, however, since in any case that calculation is going to give us the most efficient estimate of the price scatter. Whoever said here that the bands give us a measure of volatility was certainly correct -- but it is not correct to attach specific probabilities without knowing what the form of the distribution function is.

Now, there, don't you'all wish i'd go back to Foreman and his weenie roaster?

See this post in another thread:
http://elitetrader.com/vb/showthread.php?s=&postid=1355485&highlight=truncated#post1355485
The statistical distribution is called "truncated Levy flight." This was first studied by none other than Mandelbrot (of the fractal fame) back in the early 60's.
 
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