Anomalies and the Portfolio Effect, 01/13/06
There should be a portfolio effect when trading models are based on different classes of anomalies (see The First Law of Anomalies) - an effect that buffers trading results against ever-changing-cycles.
To that end, a (partial) list of classes of anomalies:
Metaphors (biology, physics, astronomy, geology, etc)
Analogies (turf betting, black jack, naval battles)
Exogenous (based on an outside time series)
Based on number systems (base 10, base 2, hex, etc)