Why is the standard deviation of the distribution of sample means smaller than the standard deviation of the population from which it came? Select all that apply. (Note: There could be more than one correct answer) Since we are only graphing the averages of the samples, extremes like the minimum and maximum of each sample are not present, making the standard deviation of the sample means smaller than the standard deviation of the population. The standard deviation of the distribution of sample means is smaller than the standard deviation of the population because a sample is always smaller than the population. According to the central limit theorem, we divide the population standard deviation σ by the square root of the sample size n , so as n gets bigger the quotient gets smaller.