To find StDev, we first have to find the mean of the squared differences. The differences between each score and the mean are 0,-2,2, respectively, giving squared values of 0,4,4. To find the variance, we take the sum of the three values and divide it by the number of values in the total set (3). This gives 8/3 or 2.6667. To find the population StDev, then, take the square root of the variance (2.6667), to find 1.633.
