Enter Average Excess Return (Alpha) and Standard Deviation of the Alpha to calculate for Number of Years Needed for t-stat of 2. A t-stat of 2 is needed to be 97.5% confident that the excess return (alpha) is not zero. x Average Excess Return (Alpha): s Standard Deviation of Alpha: t t-stat: 2 Calculate n Number of Years Needed for a t-stat of 2: