Based on the research done by Bulkowski in Encyclopedia of Chart Patterns, the highest probability patterns are high tight flags in established uptrends.
Performance rank of 1/23 in bull markets (based on his assessment of chart patterns). His study was based on 1991 - 2005 data.
From the book -
"The average rise in a bull market is 69% and patterns in both bull and bear markets have 0% break-even failure rates. Yes, they do fail, but just 5 out of 307 failed to climb at least 10%, and none failed to climb at least 5%. That is an excellent start for any chart pattern. The percentage meeting the price target, called the measure rule, works nearly all the time (90%) but is based on half the move from the trend start to the flag, projected upward."
Performance rank of 1/23 in bull markets (based on his assessment of chart patterns). His study was based on 1991 - 2005 data.
From the book -
"The average rise in a bull market is 69% and patterns in both bull and bear markets have 0% break-even failure rates. Yes, they do fail, but just 5 out of 307 failed to climb at least 10%, and none failed to climb at least 5%. That is an excellent start for any chart pattern. The percentage meeting the price target, called the measure rule, works nearly all the time (90%) but is based on half the move from the trend start to the flag, projected upward."