I am not sure the thread title is accurate or not but I am not sure how else to word. I have a data set that can contains products by month by year for a series of products. The problem lies is that each product might not start in the same month. Product 1 and 2 might start in July 2020 while Product 3 starts in March 2021. I would like to sum the total number of each product for each year. Is this possible. If so then my next question is can I use the total sum for each product for a weight average equation? Below is a snippet of my data set. Ultimately I would like to sum column f and use that sum in a weighted average equation for column G. Each year has two black rows between them. The data is sorted by product, year and then period.
Again is this possible.
Again is this possible.
