This Issue's Roundup of AT's Proprietary Alphability Metrics
Published in Automated Trader Magazine Issue 09 Q2 2008
Automated Trader's proprietary tradability metrics are environmental statistics intended to assist those building trading models/systems in determining which markets and timeframes are most favourably responsive to which generic types of model.
Trend Alphability
The Alphability stats for determining the 'trend friendliness' of markets shown here are based upon determining the amount of noise around a hypothetical trend. The simplest variant of Trend Alphability depicted here consists of the R2 (coefficient of determination) of a linear regression line plotted through the data points between the bars on which the low and high of a trading session were made (or the reverse if the high was made first). The calculation is based on the mid point of price bars in a variety of time frames. Multiplying this daily Alphability metric by the high/low range for the day (expressed as a percentage change) gives a ratio of 'trendiness' to the maximum available reward.
Reversal Alphability
Reversal Alphability follows similar general principles to Trend
Alphability in that it provides a metric for the ease or
difficulty of capturing a hypothetically optimal alpha. As the
name implies, the differences lie in the generic types of model
used. The variant of Reversal Alphability shown here is based
upon two very simple reversal patterns, the short entry version
of which is illustrated in Figure 9. For a short position the
reversal entry logic is a bar (Bar 3) with
a mid value greater than the preceding and succeeding bars (vice
versa for a long entry).
To calculate the metric, the number of reversals in a day are
calculated and divided into the sum of the percentage change of
the moves from each reversal to the next.
(Trend and Reversal Alphability are not necessarily mutually
exclusive; it is perfectly possible for an instrument to have
simultaneous high/low scores
for both.)
Score significance
Trend Alphability:
Stocks and stock index futures  above 2 extremely benign, 12 acceptable, below 1 (and especially below 0.5) adverse. Commensurate categories for bond futures are typically a third of these values.
Reversal Alphability:
Stocks and stock index futures  above 0.4 extremely benign,
0.30.4 acceptable, below 0.3 (and especially 0.2) adverse.
Commensurate categories for bond futures are typically a third of
these values.
For more information on Alphability, please see page 56 of
the Q3 2007 edition of Automated Trader or visit http://www.automatedtrader.net/Alphability.xhtm




