Enter the Average, Standard Deviation and Sample Size (Number of Observations) to calculate the t-stat. A t-stat of 2 indicates that the average is statistically significant and that you can be 97.5% confident that the average did not occur by chance. With a t-stat of 2, there is still a 2.5% probability that that the true value of the average is zero. x Average: s Standard Deviation: n Sample Size: Calculate t t-stat: