[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: Survey statistics, sampling methods

From   Steven Samuels <>
Subject   Re: st: Survey statistics, sampling methods
Date   Fri, 31 Aug 2007 09:41:01 -0400

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.


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)?

*   For searches and help try:

© Copyright 1996–2022 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index