Except that this isn't hypothesis testing. The graphs are not clearly labelled, but I'm interpreting the results as indicating that the entire population is sh

Except that this isn't hypothesis testing. The graphs are not clearly labelled, but I'm interpreting the results as indicating that the entire population is shifted. This would be a significant advantage. (If it was hypothesis testing, 1 sigma could be statistically significant depending on sample size. You might be confusing the population variance with the sample mean variance.)