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Re: st: RE: RE: Replace missing values by 0


From   David Bell <dcbell@iupui.edu>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: RE: RE: Replace missing values by 0
Date   Tue, 10 Aug 2010 12:13:58 -0400

-
In many cases, skip patterns in questionnaires leave behind missing values, either -9's or .'s.  If you told the interviewer that you didn't do behavior X in the past year, you won't be asked how many times you did X in the past 30 days.  The missing value for 30-day behavior X really does represent a zero.

Dave
====================================
David C. Bell
Professor of Sociology
Indiana University Purdue University Indianapolis (IUPUI)
(317) 278-1336
====================================




On Aug 9, 2010, at 6:29 PM, David Radwin wrote:

> Tony,
> 
> Sometimes data, especially count data, are stored in a spreadsheet where a
> blank cell indicates a zero value. For example, if the data are
> hand-entered and there are a lot of zero values, it is more efficient not
> to enter a zero, and many spreadsheet functions treat the blank cell as a
> zero value.
> 
> However, if you paste or -insheet- these data into Stata, the blank cells
> are encoded as missing values. In this case it is necessary to convert the
> missing values to zeroes.
> 
> David
> 
> --
> David Radwin
> Research Associate
> MPR Associates, Inc.
> 2150 Shattuck Ave., Suite 800
> Berkeley, CA 94704
> Phone: 510-849-4942
> Fax: 510-849-0794
> 
> www.mprinc.com
> 
> 
>> -----Original Message-----
>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
>> statalist@hsphsun2.harvard.edu] On Behalf Of Lachenbruch, Peter
>> Sent: Monday, August 09, 2010 2:59 PM
>> To: 'statalist@hsphsun2.harvard.edu'
>> Subject: st: RE: Replace missing values by 0
>> 
>> In all of the discussion of this query, nobody has asked why it is
>> important to do this?  If you are computing means, the 0 values will
>> distort the mean (or median if enough), and if you simply want to ignore
>> zeros with "if x~=0") retaining the missing value will do this
>> automatically.
>> 
>> I am unsure if I've ever had a reason to convert missing values to a
>> numeric value, but have had many times when the -9 for missing (or
>> whatever) had to be set to "."
>> 
>> Tony
>> 
>> Peter A. Lachenbruch
>> Department of Public Health
>> Oregon State University
>> Corvallis, OR 97330
>> Phone: 541-737-3832
>> FAX: 541-737-4001
>> 
>> 
>> -----Original Message-----
>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
>> statalist@hsphsun2.harvard.edu] On Behalf Of Hobst
>> Sent: Monday, August 09, 2010 1:55 AM
>> To: statalist@hsphsun2.harvard.edu
>> Subject: st: Replace missing values by 0
>> 
>> I have two variabled called "prean" and "pa_kum" that contain missing
>> values.
>> These missing values i would like to replace by 0 (zero). What command
> can
>> i
>> use to do this?
>> 
>> Thanks in advance for your support. Regards
>> --
>> View this message in context:
>> http://statalist.1588530.n2.nabble.com/Replace-missing-values-by-0-
>> tp5388239p5388239.html
>> Sent from the Statalist mailing list archive at Nabble.com.
> 
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