Weighted interquartile range

How did you compute the weighted median? According to this Wikipedia page (https://en.wikipedia.org/wiki/Weight...centile_method ), the weighted median is just a special case of the more general weighted percentile formula. I expect that you should be able to substitute something other than 50 or 0.5 (depending on the formula you used for weighted median) and get the desired weighted percentile (if I understand correct, the 25th and 75th percentile). Then compute your interquartile range.

Do you understand how gjlindn's code? It looks like, rather than use the formula described by Wikipedia, his/her UDF simply makes a new array of "weight" copies of each "value". Then uses the built in WorksheetFunction.Median() function to derive the median. By simply changing WorksheetFunction.Median to WorksheetFunction.Percentile() or .Quartile(), you could return any quartile or percentile you wanted from the UDF.

I am hesitant to "just do it for you" because this edit should be very simple. What have you tried, and what has happened with each attempt?

Here's a quick edit allowing you to see how to replace the .Median() function with either the .Quartile() function or the .Percentile() function:

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Does that help you see how to use these functions in the UDF?