It was over ten years ago when I sat in an undergraduate statistics class learning about standard deviation. Then, I didn’t understand the purpose. Today, I use it to evaluate the distribution of serial data. As far as I am concerned standard deviation will explain how widely spread and what characteristics that spread has with your data.
I have been using the Microsoft Excel formula for calculating standard deviation. This is simply =STDEV(seriesY:seriesX). BAM! – there is your standard deviation. I wanted to see the process and what it takes to manually find standard deviation without using a formula. I have included the step by step process for finding standard deviation and a spreadsheet to illustrate the point.
Manually finding standard deviation:
- Calculate the mean of your series
- Find the deviation by subtracting the reading from the mean, square result
- Sum the deviations from the series
- Take the sample series minus 1 and divide into sum of deviations
- Find the square root of the divided number to get the standard deviation
It sounds complicated, but it is really not. When you properly use standard deviation in your analysis you get a better sense of what your data is really trying to show you. Plus, there are some girls who think a guy who can do statistics is hot.
Attachment: PROCESS-Standard Deviation