# st: Perplexed by the SUM function

 From Lena Cuisina To statalist@hsphsun2.harvard.edu Subject st: Perplexed by the SUM function Date Mon, 16 Mar 2009 15:05:02 -0700 (PDT)

```I have a very basic question.  I’m adding up responses to 5 questions.  Some of the questions have missing data.  This is what I don’t want to do, because I don't want to lose the 23 observations:

. gen gh_raw = gh1 + gh2 + gh3 + gh4 + gh5
(23 missing values generated)

. gen gh_avg = gh_raw/5
(23 missing values generated)

I want to use whatever data I’ve got from the other questions in calculating the sum -- ie, I’d like to great the missing as zero, not missing.  So I tried the sum function:

gen gh_raw1 = sum(gh1+gh2+gh3+gh4+gh5)

gen gh_avg1 = gh_raw1/5

All 5 questions have the same 5-category ordinal response scale that’s coded 0, 25, 50, 75, 100.  So the average of the 5 responses are within the 0 to 100 range.  Unfortunately, the command I've written with the sum function gives me a set of average scores with a maximum of 18,800.  It’s crazy.

I have no idea what I’m doing wrong, because I’m pretty new to Stata.  Sorry for such a basic question.

Lena

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