Zacks provides a rolling ten year history of earnings surprises, including historical earnings report dates, estimated EPS as of the report date, the standard deviation of the EPS estimates, reported EPS actuals, and calculated surprise differences between estimates and actuals in both dollar and percentage terms. Under the Zacks BNRI methodology, all EPS figures are adjusted for non-recurring items and stock option expenses across all tickers. Surprise figures are calculated as the difference between the EPS estimates and reported actuals. Significant surprise figures can generate a drift effect up or down in the stock price over the following one to two weeks after the earnings report date. Alpha can be found by comparing the size of the surprise figures to stock price movements in the days following earnings reports, particularly in cases where the amount of the surprise exceeds the standard deviation of the estimate, or in cases where a company has reported a consisten series of positive surprises, then reverses course with a negative surprise or vice versa.