I am trying to calculate the cumulative attendance percentage for students each week as the 12-week term progresses. A copy of the worksheet is attached for reference.
I have a spreadsheet with either an "A" or "P" in cells across a row which includes other data for a given week number. "A" is for 'absent'; "P" is for 'present' in the 'ATT' column for each week. There are 12 weekly sections to the sheet. None of the other data in the rows is either an "A" or "P", other than the data in the 'ATT' fields. I have added a percentage column (ATT %) to hold the cumulative calculation formula of the ratio of "A"s to "P"s in each weekly section using the current week and all previous weeks to-date. (For Week 3, for instance, the calculation would include the ratio of "A"s to "P"s for Weeks 1, 2, and 3.)
See the attached sheet for details.
The idea is to capture the percentage of "P"s to "A"s for each week as each week progresses. The calculation for Week 1 is simple and is already done (Column F). What is more complex is how to do this average for Weeks 2 through 12 so that it is cumulative through the current week to-date. The result would go in the 'ATT %' cell for each week, starting with cell U3 for Week 2, then cell AJ3 for Week 2, AY3 for Week 3, etc. across the sheet through Week 12 for each 'ATT %' column in the row.
As you can see, I have conditionally formatted cell F3 so that it is green if the attendance percentage is 95% or above. I can take care of doing the conditional formats for the other 'ATT %' cells so they shade the way I want them to, so that is not a problem.
What is the formula I could place in the "ATT %" cell for each week to calculate this cumulative percentage based upon whether an "A" or "P" appears in the current week and previous weeks to-date in the "ATT" column for each week? For instance, say, in Week 8, the calculation would be based upon the ratio of total "P"s to total "A"s cumulatively for Weeks 1 through 8 and would appear in the "ATT %" cell in Week 8. This formula will be replicated down each "ATT %" column through row 29 to get the average for each student in the course.