Cases and Controls

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

Dr. Long,



Your statement that the percent of smoking cases need to match 

the percent of smoking controls in a case control study is 

erroneous.  I am sure if this was a fatal flaw with the study, the 

American Journal of Epidemiology would never of published it.  If you 

think it is a flaw, why don't you write a letter to the editors of 

the journal.  The AJE is the most pretigious epidemiologic journal 

published.  Most people with training in Epidemiology would know that 

in a population-based case-control study, such as Iowa, the controls 

represent the population of subjects in the state who have not 

developed lung cancer.  The researchers in the Iowa study matched 

their cases to controls by 5 year age groups and gender.  Researchers 

routinely have some factors risk factors that are not balanced.  The 

nice thing about a case-control study, unlike an ecologic study, is 

that there are routine procedures to adjust for the effect of smoking 

since you have individual smoking data.  



I see from the archieves that Dr. Raabe discussed this previously on 

the list.



Overall, I think Dr. Field provided a more substantial and defensive 

view on the radon debate than Dr. Becker.











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