Backtesting is not only a way to check signal accuracy, but also a tool to continually improvement. Data can be used for self adjustment as each stock have a individual behavior. Accuracy and return is not the same. A stock signal may provide low statistical accuracy, but the signals may prove high return in average. Sharp market dips or fundamental changes (earning reports, news updates etc), may force a short term reaction and disturb the signals (Signals may jump quickly from buy to sell, just to return to buy).
|2019-01-23 - 2019-02-15||BUY||0.12|
|2019-01-22 - 2019-01-23||SELL||-0.12|
|2019-01-17 - 2019-01-22||BUY||0.12|
|2019-01-15 - 2019-01-17||HOLD||0.28|
|2019-01-11 - 2019-01-15||SELL||0.36|