>>Thanks for the reply J.C.
>>
>>I saw the VFP documentation that says that it ignores NULL values. If it does, then why is it that x is not NULL? As you can see from my example code, I initalize x to NULL first then call the CALCULATE command.
>>
>
>If you calculate an AVG() on a field in a table with no records, you get 0.00 as the result. As far as the CALCULATE command is concerned, your table has no records.

I made a test table and tried it. CALCULATE returned 0.00 and

select avg(tt) from test into array atest

returned NULL
?atest[1]

So, we should know about this "feature" and use SQL if possible. However, SQL works with the disk table, while CALCULATE, AFAIK, works with buffered table...