Re: st: Survey statistics, sampling methods

[Steven Samuels <sjhsamuels@earthlink.net>]

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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