December 2005Trading Tip:
Hull Moving Average by Alan
Hull www.alanhull.com
The Hull Moving Average solves the age old dilemma of making a
moving average more responsive to current price activity whilst
maintaining curve smoothness. In fact the HMA almost
eliminates lag altogether and manages to improve smoothing at
the same time. To understand how it achieves both of these
opposing outcomes simultaneously we need to start with an easily
understood frame of reference. The following chart contains a
16 week simple moving average which constantly lags the price
activity and has poor smoothness.
Firstly, solving the problem of curve smoothing can be
done by taking an average of the average, i.e. 16 period SMA(16
period SMA(Price)). The bad news is that it causes a huge increase
in lag as seen below.
Solving the problem of lag is a bit more involved and requires an
explanation with numbers rather than charts. Consider a series
of 10 numbers from '0' to '9' inclusive and imagine that they are
successive price points on a chart with 9 being the most recent
price point at the right hand leading edge. If we take the 10
period simple average of these numbers then, not surprisingly, we
will determine the midpoint of 4.5 which significantly lags behind
the most recent price point of 9. Here's the clever bit…first
let's halve the period of the average to 5 and apply it to the most
recent numbers of 5,6,7,8, and 9, the result being the midpoint of
7.
Finally, to remove the lag we take the midpoint of 7 and add the
difference between the two averages which equals 2.5 (7 - 4.5). This
gives a final answer of 9.5 (7 + 2.5) which is a slight
overcompensation. But this overcompensation is very handy
because it offsets the lagging effect of the nested averaging.
Hence the result of combining these 2 techniques is a near perfect
balance between lag reduction and curve smoothing.
The HMA manages to keep up with rapid changes in price activity
whilst having superior smoothing over an SMA of the same
period. The HMA employs weighted moving averages and dampens
the smoothing effect (and resulting lag) by using the square root of
the period instead of the actual period itself…as seen below.
WMA (2 x WMA(Price,Integer(Period/2)) -
WMA(Price,Period),Integer(SquareRoot(Period)))
The following formulas for the Hull Moving Average are for Ensign Windows but
can be easily adapted for use with other charting programs that are
capable of custom indicator construction. A template
named HullAverage can be downloaded from the Ensign web site using
the Internet Services form in Ensign Windows.
The HullAverage template has taken the visual of the
Hull Average line one step further by plotting the study line in
rising and falling colors of Green and Red using the dual color line
marker on Line J. (This template requires Ensign Windows with
a version date of 12-29-2005 or later.)
Trading Tip:
Bradley Model 2005 Update by Howard Arrington
An article about the Bradley Stock Market Model was published in
the November
2002 issue of Trading Tips newsletter and updated in the May
2004 issue. Now that 18 months have gone by, it is time
for a follow up article to document the correlation of the Bradley
model for 2005 with the stock market.
The Bradley model is a forecast of the market based on
astrological relationships. Because astrological
relationships can be defined with mathematics, the Bradley forecasts
can be made decades in advance. The following chart
shows how the Bradley model correlated with the stock market in
2005.
The end of 2004 and the first two months of 2005 had
excellent correlation with the timing and direction of the turns in
the market. However, in my opinion, it would have been
difficult to trade the stock market using the Bradley model for the
balance of 2005. For a portion of the summer and fall, there
is better correlation with the market if the Bradley model is
plotted inverted.
There are three characteristics of the Bradley
forecast: time, direction, and
price. Each of these will be discussed.
The primary characteristic to be extracted from the
Bradley model is time. The model is basically a clock
based on the motions of objects in our solar system. We
readily acknowledge the influence in our lives of the daily rotation
of the earth, and the monthly orbit of the moon, and the cycle of
seasons from the annual orbit of the earth around the sun. But
beyond those three accepted astronomical clocks, skepticism
increases that life on earth is also influenced by other
astronomical bodies. It is hard to accept that other
astronomical bodies have any influence on the business cycles of the
economy of the United States or the world. But that is what
the Bradley model is attempting to show. When the timing of
market turns is in synch with the Bradley forecast as was the case
for the turns in December 2004 (top), January 2005 (bottom) and
February 2005 (top), the forecast can be very impressive.
As is shown in the 2005 chart, the market and the
Bradley forecast can be out of sync. For example, the
two turns in August 2005 were well aligned for time, but out of sync
for direction. The market put in a top in mid
August when the forecast was for a bottom turn. And the
market made a bottom swing at the end of August when the forecast
was for a swing top. When this happens, the forecast is
described as being 'inverted'. The timing of the turns
is still well aligned or correlated. It is the direction into
these turns that is inverted. Why does inversion
happen? Answer: I do not know and I have not
found a good answer from those who regularly work with the Bradley
model. Is there a way to know in advance when inversion
will happen? Answer: No. You can suspect the
model is inverted when it is happening, and still take advantage of
the time forecast.
The third characteristic is price, and this
should have a low priority in comparison to time and
direction. The Bradley data values are in the
range of -200 to 200 and thus to plot the Bradley forecast, the data
set has been resized and repositioned so that it shows on the INDU
chart as an overlay. The Bradley curve has been stretched and
shifted vertically until the curve fit nicely on the INDU
chart. How the curve is shown on the chart is completely
arbitrary for the convenience of seeing the Bradley curve near the
market data. At times there is good correlation in comparing
the size of one Bradley swing with another and seeing a similar
ratio in swing amplitudes in the market. At other times, there
is no price correlation. The 2005 Bradley model suggested the
annual top of the market would be in July 2005. There
was a swing high in the summer, but it definitely was not the top of
the market for 2005. The stock market's 2005 top
occurred in March with a retest of that top in November 2005.
Be sure and read the other two articles about the Bradley model
to see other examples where there was better correlation between the
forecast and the market than was experienced in 2005.
Neither article shows the full correlation for 2004 so the 2004
chart is shown here.
This update on the Bradley model concludes by showing the
forecast for 2006. Only time will tell whether the market and
the forecast will be well correlated, or inverted, or down right
useless as a tool for trading the stock market. The forecast
does not show a price scale on purpose. Use the curve
primarily for timing the turns, and then secondly for the direction
into those turn dates. In general the model shows an up
trend for the first half of 2006 and then a down trend into
Thanksgiving. However, the forecast into the end of 2005
appears to be inverted, so the 2006 forecast may also be inverted in
part or in full.
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