Good morning Math Experts, I am having difficulty figuring out how to calculate the standard deviation for a set of data.
Here is the request from my user: Going back three years from today, calculate the yearly average of contacts an officer has with a citizen and the standard deviation of the yearly average across a department.
So I have counted all the contacts in the three year period and counted all the officers that made those contacts averaged that and divided by three to get a single year average:
How can I calculate the standard deviation of this data at the ONE year level? Am I even calculating the one year average correctly?
I feel like maybe I am making this too complicated but don't think the answer the SQL STDEV() function is giving is correct. I am using SQL server query but can use R if that makes it easier.