County Data

["John Williams" <JohnWi@law.com>]

Dr. Cohen,



You stated below, "Statistics is also an important issue as many 

counties have less than 5 cases per year."



I think that was one of the points Field, Smith and Lynch made in 

their Health Physics Forum paper about your study.  If you only have 

5 cases per county, the statistics are a problem for you in an 

ecologic study.  How can you represent the whole county with such 

scant data per county.  The mortality data is not quality data and 

you have very little data for each county.  The major limitation of 

ecologic studies is the quality of data and you just admitted that 

the data is lacking.  That is why you should start by focusing on the 

states that have SEER quality data and lots of counties like Iowa.  

Just because you have a lot of counties (and therefore data), that 

does not mean you have more confidence in your data if your 

underlying county by county data is suspect.  These errors do not 

average out over the United States, but rather get propagated with 

the addition of each county.  



John Williams. 

    











 Field's incidence data is that different time periods were covered. 

We

used 1970-1979 in the original paper and 1979-1994 in the Update 

paper;

there was little difference in national results between them. 

Statistics

is also an important issue as many counties have less than 5 cases per

year.

Since my studies cover the entire nation, there was little choice

for me in using mortality data. Moreover, all of the problems 

considered

in this discussion should average out in considering data for 1600

counties from all over U.S. To matter, there would have to be a strong

correlation between these problems and radon levels, extending all 

over

the nation. There would be a much better chance for such a correlation

within a single state.



Bernard L. Cohen

Physics Dept.

University of Pittsburgh

Pittsburgh, PA 15260

Tel: (412)624-9245

Fax: (412)624-9163

e-mail: blc+@pitt.edu

 







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