SUMPRODUCT(--(RawMarketers=$C$3),--(RawDateGap))/(SUMPRODUCT(--(RawMarketers=$C$3)))

RawMarketers and RawDateGap are names for specific columns, where RawMarketers = names of various marketers and RawDateGap = the amount of time between when appointments they create. In this formula, I am attempting to get the average daily gap between appointments.

Unfortunately, in my RawDateGap column there are blank cells where there should be numbers, simply because the data cannot be counted for those appointments, so no data exists.

I am not sure how to find the average gap, if this is the case.