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Re: [LUG] OT:Agricultural Census 2010

 

On Wed, 2010-02-03 at 15:06 +0000, richard wrote:
snip
> for their justification  of their  method see ;
> http://www.defra.gov.uk/esg/work_htm/publications/cs/farmstats_web/1_ABOUT_THE_SURVEY/FAQs_ABOUT_THE_DATA_AND_SURVEY/Introduction.htm#samplingstrategy
> 
The sampling seems OK to me. Even though they "sample" all the biggies,
they sample from all their strata and multiply up to estimate the
contribution of all strata.

The key para is
Within each stratum holdings are sampled at random. The only exception
to this is amongst the smallest holdings where a partially systematic
approach is adopted to ensure that individual holdings are not usually
sampled in successive years. This departure from randomness does create
some risk of bias, but this risk is small, particularly since this
stratum makes a relatively small contribution to the national totals for
most crops.

James
> 
-- 
james kilty
http://www.kilty.demon.co.uk


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