range ? what range ? The Bands are moved with the MOVING average by construction so it is no more a range it just an EXTRAPOLATION that follows the price haha ! It was supposedly based "scientifically" on student test which gives the prob of 95% (for 2 standard deviation) but in student test the mean is fixed it is not moved at each increment so that the "scientific" adjective is rather a bullshit (there is another statistical flaw about this student test interpretation but it's too technical I won't talk about it here). I don't mean that BB is not useful but it is not as rigorously based as advanced.
And what do you mean by psychology ? If one buys a chicken in a supermarket do you include this in your psychological reason case ? Because if your definition of psychology cause is large enough it can englobe all activities for sure so that it will become a TOE (Theory Of Everything hee hee ) but is it still useful since it will be too much fuzzy ?
Last but not least, if psychological cause has any justification, it is in the case when the bands are "exploded" and so behave out of "normal" random law - see again Mandelbrot's article about 10 standard deviations - so it is funny that you pretend that things are psychological because price is contained within bands since if things behave smoothly in market there wouldn't any scientific research about the reason behind hystery of market and advance the hypothesis that market COULD (because it's not demonstrated) be driven by the psychology of crowd.
And what do you mean by psychology ? If one buys a chicken in a supermarket do you include this in your psychological reason case ? Because if your definition of psychology cause is large enough it can englobe all activities for sure so that it will become a TOE (Theory Of Everything hee hee ) but is it still useful since it will be too much fuzzy ?
Last but not least, if psychological cause has any justification, it is in the case when the bands are "exploded" and so behave out of "normal" random law - see again Mandelbrot's article about 10 standard deviations - so it is funny that you pretend that things are psychological because price is contained within bands since if things behave smoothly in market there wouldn't any scientific research about the reason behind hystery of market and advance the hypothesis that market COULD (because it's not demonstrated) be driven by the psychology of crowd.
Quote from jbtrader23:
Bollinger Bands are simply one tool of measuring standard deviation. You could use a % away from the 10 day moving average for example and calculate standard deviation from that. You could calculate standard deviation over the 200 day moving average. There are literally infinite possibilities.
I still find it remarkable that all securities tend to stay within this 95% range though. Even in the biggest bubbles in the history of the world (Japan, Nasdaq 1999, Gold in 1980, etc), the markets never went much above 3 standard deviations.
My question is, at the upper extreme of 3 standard deviations, there is obviously mass crowd pyschology at work. Everyone is euphoric. Go back to when BRCM or ARBA were going up $50 a day in a near vertical ascent. Occasionally there'd be days outside the bollinger band. But it very rarely lasts. Try finding a stock chart in which prices go completely outside the band for many days at a time. How about for a few straight weeks? It never happens. Wouldn't random walk theory suggest that stocks could go up for 30 days in a row for example. After all its a 50-50 random chance stocks can go up or down for a day. If you toss a penny enough times, statistically, you'll get 30 straight heads eventually. Even with a hundred years of stock data, I dont think stocks have ever gone up or down for 30 days in a row for example. I believe record up days in a row for the DOW is somewhere around 10 or 12.
I think stocks charts are simply a graph of mass crowd pyschology, nothing more. And throughout human history, even if you took a chart of dutch tulips in 16th century Holland (I'd love to see a chart of that by the way), I think you'd find the same patterns that you'd find in modern day markets. Even though many novice traders think "it's different this time" (i.e. we're smarter than the dutch tulip traders, we're more informed than the participants in the crash of '29 etc), we still behave exactly the same way they did.
The chart of Japan overlapped with the S&P is amazing. Even two completely seperate events (the Crash of '87 and the crash of '98), appear very similar on the chart. Japan was the first major market in the world to eclipse it's previous '87 high and thus added fuel to the fire for the bubble believers. Likewise in '98. The NASDAQ shot over its previous high and was off to the races.
. It's somehow the same thing when I say that psychology is not primary cause, I don't deny that psychology exists in stock market and can play a role, I pretend that it is only secondary comparatively with what I have discovered as other underlying mechanism. That is to say you can use psychology to help you analysing the market but It will always stay fuzzy even if quantified by model like the one of Sornette or others it stays stochastic approach with loose prediction inherent to this type of model.