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From | Maarten buis <maartenbuis@yahoo.co.uk> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Re: st: Calculate response rate (proportion of non-missing value) |
Date | Mon, 14 Feb 2011 08:40:40 +0000 (GMT) |
--- On Mon, 14/2/11, Guo Chen wrote: > I have a survey data right now and need to calculate the > response rate to each question by whether the interviewee > is in a group, and then do a ttest of the response rates > between the two groups of people. To get the response rate you need a dumy variable that is 1 when the respondent answered to that question and 0 otherwise. The -missing()- function gives you exactly the opposite. If you precede that with a -!- you reverse the logical statement. Without thinking about it I literally read -!missing()- as "not missing". For more on this see: <http://www.stata.com/support/faqs/data/trueorfalse.html> and an application of this logic on this text on one of my T-shirts: <http://www.stata.com/meeting/13uk/i/mbuis_talk_big.jpg>) Once you have that dummy, then the rate is just the mean of that dummy. For convenience you can us -ds- to get a list of variables you want to test, and use a -foreach- loop to loop over that list, but that is just icing on the cake; it saves you typing (and thus diminishes the chance of a typo...). *-------------------------- begin example ------------------- sysuse nlsw88, clear ds race, not local varl "`r(varlist)'" // other (3) and missing values will be turned into missing // so 1 is black, 0 is white gen black = race == 2 if race <=2 gen byte miss = . foreach var of local varl { qui replace miss = !missing(`var') di "================= testing response rate for `var'" ttest miss, by(black) } *-------------------------- end example ----------------------- (For more on examples I sent to the Statalist see: http://www.maartenbuis.nl/example_faq ) Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/