Column formula for average value when some cells are null

I set up a spreadsheet to allow a group of people to rate a list of items. Each item is a row in my spreadsheet, and each person has a column, where they can choose 1 to 5 stars. I need to calculate the average rating for each row. Some people did not provide a rating for each item in the list, which means that the denominator in my average formula needs to be different for each row. Is there a way to set this up as a column formula, or do I need to set up a separate formula for each list item?

You can work with a column formula like


The key point to note is the functions need to have columns specified explicitly.

Column formulas can only contain references to columns or to fixed cells , not relative cells or ranges.

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