Re: Re: County Data

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

--I said 5 cases per year. My 1995 paper summed cases over a 10

year period, and my 2000 Update paper summed cases over a later 15 

year

period.



-------------------------------------------------

So from some counties you actually have 65 data points.  But, now you 

are not adjusting for trends in cancer, but merely averaging them out 

with the aggregated data over a 15 year period. Smith pointed out the 

problems with temporal changes.  I would have preferred to see 65 

points per county 20 years before the lung cancer was identified.-----

------------------------------------





 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.



--The number of cases in the SEER data is much less than in my

data because they have only 5 years to sum over



----------------------



They can sum up the numbers back to the 70s if you like, not just 5 

years.



------------------------------------------





> 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.

k

--Calling data "suspect" is misleading; you should say "has

statistical limitations". If you can explain your last sentence above.

please do. Every data point from any study has statistical 

limitations, so

you are saying that the more data points you have, the less reliable 

are

your results. 

------------------------------



In the case of your data, I think that is a true statement. Not even 

to mention the cross-level bias.  So the more erroneous county data 

you have, the more error you have overall.  The error does not 

average out, just as the geologic potential for radon does not follow 

county borders.  There is a lot more variation within counties than 

between counties as far as radon potential. With the aggregate data, 

you can not capture the county variation with 65 measurements 

representing in many cases well over 100,000 homes. Why not start 

with a state like Iowa that has 1% of the U.S. population, a quality 

SEER Registry, high radon, and a lot of counties?  The inverse rate 

should be higher there since the radon is higher, right?





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