Function to replace division by zero error cells with blank cells when calculating a numeric average

Question

Hi everyone,
I have a five sheet spreadsheet that uses data from four sheets to calculate numeric averages in the fifth. The problem is that there is not always data in all four sheets which produces a division by zero error in the averages sheet. Is there a function or setting in Numbers 2.3 (not yet ready to upgrade to Numbers 3) that will allow these division by zero cells to be replaced by blank cells.
I have tried using statements of the form =AVERAGE(IFERROR(Sheet 1::Table 1:: B4,""),IFERROR(Sheet 2:: Table 1:: B4,""),Sheet 3:: Table 1:: B4,""), Sheet 4:: Table 1:: B4,"")). however instead of a division by zero error this produces an error telling me "the function AVERAGE expects that a number, date or duration but found "." ". It looks as though I will have to make about 400 changes to my sheet as these errors are in this and approximately 100 other cells!
I am hoping that there is some way if possible of correcting these errors without having to manually edit each cell individually.
Thanks,
Hugh

Answer 1

Hugh,
You may want to consider an intermediate sheet to handle the errors and then pass the result on to the main sheet.
In the following mockup, I've created a small interposing table the consists of a list of sources in column A and the result from each table. In the example, I perform some operation on those intermediate results, to be passed on to the main table. This may not be a good example, and since I don't know the overall goal of your project it's just a surrogate. (In real life we probably wouldn't be interested in finding the average of averages.)
The expression in Summary::B2 is:
=IFERROR(INDIRECT(A&"::B4"), "SourceError")
Regards,
Jerry