Today we continued looking at patterns in birthdates, and concentrated on the early space era astronauts, those of the Mercury, Gemini, and Apollo missions. There is a definite spike for the month of March. To examine the numbers better, we manually calculated the standard deviation of the data set using both the regular method and the shortcut formula. Our manual calculations gave us the same number (and mainly, provided Jared with an understanding of how the formula works) while Excel gave us a different number. This taught us an important lesson: that before using software blindly, it is very important that the principles behind the software are fully understood. We scrutinized the formula used by Excel (in the info section), and it corresponded to the one we were using... Therefore, we must have been inputting the data erroneously in Excel. This example makes one think of how prone to error we can be when we don't understand our tools.