I have a file with sales quantity per week. I now need to calculate the standard deviation where the sales quantity is grouped by a number of weeks. The number of weeks is entered in to a input field by the user.
So i have week 1 10 pcs week 2 20 pcs week 3 5 pcs week 4 25 pcs. If the user inputs 2 weeks my calculation of the standard deviation would be like stdev(30,30)