What
do the different
parameter values really mean
to the trader?
Most of us have
heard this from someone in our trading past:
"You should really use this parameter, it
really works." But why? And what do those
parameter changes really mean? How does
altering these numbers make such a difference?
And if you talk to enough traders you end
up with an equal number on both sides of
the fence. So, in this issue we are going
to do our best to explain what these parameters
really mean.
Quick overview
of the Relative Strength Index (RSI)
The RSI was first
published by Welles Wilder Jr. in 1978.
His book, New Concepts in Technical Trading
Systems, is a must read for any technical
trader.
The RSI
is an indicator that measures the changes
between the higher and lower close prices.
These price differences are plotted on a
scale from 0-100. (For more details read
report on RSI)
The formula
to RSI:
RSI=100-(100/(1+RS))
and
RS=(average of 'n' days that close up) /
(average of 'n' days that close down)
where
RSI = relative strength index
n= predetermined number of days
The parameter:
It's that 'n'
that people keep changing. But what number
should you put in? And what is the difference?
First, the 'n' represents the number of
trading days to be used in the calculations.
RSI-14 means there are 14 trading days used
in the calculation, and RSI-10 means there
are 10 trading days in the calculation and
so forth. In actuality, you could put in
whatever number you wanted, but changing
that number has a dramatic effect on when
and if signals occur.
Originally, Welles
Wilder Jr. used the 14-day RSI (half a lunar
cycle). This was later changed by traders
to 10 days (which allows for weekends) and
is exactly two weeks. The 14 -day RSI is
almost three weeks (there are five trading
days per week).
In my opinion,
the power of technicals has more to do with
the ability to alter these parameters to
fit the time frame that suites your trading
style, and less to do with the fact that
it takes the moon 28 days to circle the
earth or because 10 days fit into two business
weeks.
Parameters
should be based on your trading time frame.
A short-term trader needs a more sensitive
indicator, using smaller numbers while a
long-term trader can use a larger number
of trading days in their formula.
To figure out
what parameter fits, you need to answer
the following questions:
- Are you
a short-term trader? Using smaller numbers
for your parameter will make the indicator
more sensitive to recent price moves and trigger
signals more often. However, the older data
is ignored (it is more difficult to apply
the longer term trend lines). So if you trade
a longer term and use a small parameter, you
can be whipsawed. It is also more difficult
to draw accurate trend lines since the indicator
is more volatile (moves quickly up and down).
Are you a long-term trader? Using larger
numbers for your time frame ensures that
older prices movements are still accounted
for. Signals are generated less often
and sudden price movements are averaged
out. On the flip side, the larger your
parameter, the less sensitive the indicator
and you may miss your opportunity (since
it shows up less often in screeners) or
react late.
It is
important to note that you should test new parameters
or indicators with a risk-free paper trading
technique or try it in conjunction with your
current trading system.
| Signals
given by the RSI
Extreme
values:
Crosses
extreme values, 70/30. The 70% and 30%
levels are used as warning signals. An
RSI above 70% is considered overbought
and below 30% is considered oversold.
Double
Tops and Bottoms
Traders
watch for double tops or what Wilder referred
to as "failure swings." If the RSI makes
a double top formation, with the first
top above 70% and the second top below
the first, you get a sell signal when
the RSI falls below the level of the dip.
Conversely, a double bottom at or below
30% (with the first low below 30% and
the second at or above the same level)
gives you a buy signal when the RSI breaks
above the previous peak.
Divergences
and Convergences
Trend
of the RSI relative to the trend of the
price is where a trader sees the convergences
or divergences. A convergence is when
the price is downtrending, yet the RSI
begins to uptrend (the to lines converge).
A converegence is used as bullish warning
signal to the trader. A divergence is
then the price is uptrending and the RSI
begins to downtrend (the lines separate).
The divergence is a bearish warning signal. |
Examples
of the different RSI's
The
DJIA and the RSI-10 and RSI-14

The
DJIA and the RSI-10 and RSI-21

Quick
overview of stochastics
The
stochastic indicator, developed by Dr. George
Lane, is a momentum oscillator that can warn
of strength or weakness in the market -- often
well ahead of the final turning point. It is
based on the assumption that when a stock is
rising it tends to close near the high and when
a stock is falling it tends to close near its
lows.
There
are two types of stochastic formulas in practice
today. The original stochastic is sometimes
referred to as the "fast" stochastic to differentiate
it from the "slow" stochastic. Some traders
feel the fast stochastic %K line is too sensitive
and, to improve their analysis, they replace
the original %D line with a new slow %K line.
The new slow %D line formula is then calculated
from the new %K line. The result is a pair of
smoothed oscillators that some traders believe
provide more accurate signals.
The
slow stochastic is an excellent example of where
the strength of parameters can be seen. In the
following example I have chosen a 9,3,3 and
21,9,9.
The
first number represents the period, this is
the time frame which is used to find the highest
high and the lowest low (within the last X days,
the X is the period). The second number is the
moving average to be used in the formula and
the third number is the %D.
Once
again, the lower the numbers, the more sensitive
the indicator becomes to recent events. Larger
numbers smooth out the line. This can be seen
most easily when comparing a short slow stochastic
parameter setup and a long slow stochastic parameter
setup.
| Signals
given by the slow stochastic
The
Stochastic Oscillator generates signals
in three main ways:
-
Extreme values when the 20% and 80%
trigger lines are crossed. Buy when
the stochastic falls below 20% and
then rises above that level. Sell
when the stochastic rises above 80%
and then falls below that level. The
pattern of the stochastic is also
important; when it stays below 40-50%
for a period and then swings above,
the market is shifting from overbought
and offering a buy signal. And vice
versa when it stays above 50-60% for
a period of time.
-
Crossovers between the %D and %K lines.
Buy when the %K line rises above the
%D line and sell when the %K line
falls below the %D line. Beware of
short-term crossovers. The preferred
crossover is when the %K line intersects
after the peak of the %D line (right-hand
crossover). Crossovers often provide
choppy signals that need to be filtered
through the use of other indicators.
-
Divergences between the stochastic
and the underlying price. For example,
if prices are making a series of new
highs and the stochastic is trending
lower, you may have a warning signal
of weakness in the market.
For
a more conservative approach, extreme
values should be used as the warning signals
and the follow through the 50 line for
the confirmation of the trend change.
Some traders also state that by moving
the extreme values to the 10 and 90 lines
ensures a more reliable signal. |
Examples
of the different slow stochastics
The
DJIA and the slow stochastic 9,3,3 and 21,9,9

Summary:
The
general rule of thumb with the RSI, slow stochastic
or any indicator/oscillator, is that when you
increase the parameter, the indicator "smooths
out." Larger numbers for parameters make the
indicator less sensitive to recent moves and
the longer-term trend is more apparent. When
you decrease the parameter value, the indicator
becomes more sensitive to the recent price moves
and allows the trader to react more quickly.
The shortfall to this is that the indicator
no longer shows the longer-term trend well and
may report signals during a correction rather
than a breakout (which are what some short term
traders are looking for).
TIPS
& TECHNIQUES - Using this combination of indicators
The
RSI and stochastics work best with a complementary
indicator. According to Bollinger, one of the
biggest mistakes in technical analysis is the
multiple counting of the same information. For
example, using different indicators all derived
from the same series of closing prices to confirm
one another. So always be aware of what an indicator
uses for it's calculations and keep a balanced
system.
This
is not to say that using two of the same type
indicator with different parameters isn't helpful.
There are quite a few systems that rely on the
crosses of multiple identical indicators (for
example: the 5 & 20 moving average cross).
In the
stochastics indicator example, using both parameter
settings can give the trader an edge by identifying
both the short-term moves and the long-term
trend. Use the parameter 21,9,9 to trade only
the major uptrend and use 9,3,3 to swing trade
within the uptrend.
Putting
ChartFilter into Context
While
RSI and slow stochastic are excellent charting
indicators, there are also some valuable RSI
and slow stochastic signals you can screen for.
If you do not have an account for the StockScreener
and StockTools, click
here to sign up for free.
| RSI
- Relative Strength Index Screening/Chart
examples: Click
for report on Relative strength index (RSI)
Buy
when RSI has crossed below 30, formed
a bottom, and then crossed back up through
30.
Sell when RSI has crossed above
70, formed a peak, and then crossed back
down through 70. |
Possible
Screens, from 0 - 200 days ago

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| Charting
Sample 
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| Slow
Stochastics Screening/Chart examples:
Click
for report on Stochastics (Slow)
Buy
when Stochastic has crossed below 20%,
reached 5%, and then crossed back up through
20%.
Sell when Stochastic has crossed
above 80%, reached 95%, and then crossed
back down through 80%.
Buy when the %K line crosses above
the %D line
Sell when the %K line crosses below
the %D line. |
Possible
Screens, from 0 - 200 days ago


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