SUM function and missing value

William_Anthem — Tue, 18 Jun 2019 16:41:08 GMT

Can anyone please clarify the following for me? I have two different answers from certification practice exams and I really don't understand. Example 2 makes sense to me...SUM ignores missing values. But then there's Example 1 that uses SUM but in that one "missing" makes the total SUM missing. Any clarification is greatly appreciated - thanks!

Example 1

ACredit = . ;
BCredit = 1;
TotalCredits = sum (ACredit + BCredit) + 2;
    What is the value of TotalCredits? Answer = Missing numeric value
    Explanation: when the SUM function is called with a single argument, it returns the value of that argument. In this case, it is called
    with a missing value, so it returns a missing value.

Example 2
ACredit = . ;
BCredit = 1;
TotalCredits = sum (ACredit, BCredit) + 2;
What is the value of TotalCredits? Answer = 3
Explanation: The SUM statement ignores missing values.

Re: SUM function and missing value

Reeza — Tue, 18 Jun 2019 16:52:50 GMT

The ACredit+Bcredit is evaluated first inside the brackets and returns a missing value to SUM() which then returns a missing value again.

Re: SUM function and missing value

William_Anthem — Tue, 18 Jun 2019 19:18:35 GMT

Thank you Reeza, that explains it very well!

I appreciate your help!

Bill

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SUM function and missing value

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