Re: st: Survey statistics, sampling methods

[Jen McCormick <jenmc@stanford.edu>]

I appreciate the input.  Jen

Steven Samuels wrote:
> Jen, I share Stas's opinions.   You made the classic mistake of 
> selecting too few primary sampling units and trying to make up for 
> this with lots of observations at later stages.  Still, if you can get 
> help from an exprerienced survey researcher, you might salvage 
> something even now.  If, as in my experience, the response rate from 
> graduate students is abysmal, I would just drop them from the analyses.
>
> Steven
>
> On Aug 30, 2007, at 4:27 PM, Jen McCormick wrote:
>
>
> > Hi   -
> >
> > My colleague and I conducted a national survey to determine the 
> > attitudes of life scientists toward the ethical and societal 
> > implications of their research.  We sent 2000 surveys to life 
> > scientists at 7 different research universities.  We received 855 
> > surveys back and in addition, had about a 10% rate of no contact so 
> > our response rate is about 50%.
> >
> > We used departments as our secondary sampling unit.  We categorized 
> > all the life science-related departments at our institution as either 
> > basic science or clinical and then randomly selected 3 from basic 
> > science and 2 from clinical for a total of 5 departments (secondary 
> > strata?) from which we pulled individual researchers. Across the 7 
> > different institutions there is on average about 21 departments that 
> > would fall into our definition of life science-related departments.
> >
> > We are not quite certain what our finite-population correction 
> > factors are for the universities strata  and for the department 
> > strata but think these are  1/13, 1/13, 1/45, 1/19, 1/4, 1/3 and 
> > 5/21, respectively  Are we correct in thinking we need to make use of 
> > these ratios?
> >
> > The unit we actually surveyed is the individual researcher (graduate 
> > students, postdoctoral fellows, research staff, and faculty).  
> > Sampling was done based on position at this point (i.e. we put all 
> > grad students from university 1 in one list and then randomly 
> > selected about 66, we put all postdocs from university 1 in one list 
> > and then randomly selected about 66, etc).  Selected about 250 
> > individuals from each of the 6 universities (a few minor exceptions) 
> > and 500 from Stanford.  We also tried to get equal numbers from each 
> > of the four position categories as best as possible. How do we 
> > include this into our use of the svyset command (or do we need to not 
> > worry about this)?
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