Accuracy Revisited

Consider the following language from an online ad promoting trading advice:

A. Has been 81% correct on long and short trades in the S&P 500 Index between 1/03/1994 and 4/12/2004.
B. Offers you swing trading opportunities almost daily in widely traded stocks such as AMAT, YHOO, INTC, KLAC and many more.
C. Had only one losing trade out of 11 in the SPYs in all of 2003.
D. Was correct on nearly 80% of all trades (long and short combined) in the Nasdaq-100 during the 2000 – 2002 bear market.

Sound too good to be true?

You might like my 2017 epic release: Trend Following: How to Make a Fortune in Bull, Bear and Black Swan Markets (Fifth Edition). Revised and extended with twice as much content.