Definitions of study designs - correction

In my post, I forgot to mention something that is

especially relevant concerning the NSWS. Below is the

way the sentence should read (correction is in ALL

CAPS):

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

> The goal of an occupational cohort study is to

> examine

> a cohort of workers in an industry vs. an unexposed

> cohort, matched for age and gender, to see if the

> exposed workers are experiencing an elevated risk of

> any disease OR ARE EXPERIENCING ANY DEFICITS IN

MORTALITY from a factor or factors at work.

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

It should be noted that deficits in mortality are to

be expected in workers are compared vs. the general

population. Deficits of mortality should be

investigated further, however, if they occur when two

groups of workers equivalent (stratified by age and

number of years worked) except for an occupational

exposure, are compared with each other.

There is a 'progression' in suggested study designs

here. The mortality deficit result of a cohort study

suggests a randomized controlled (clinical) trial.

This is why a randomized controlled trial of a level

of low LET radiation equivalent to that experienced by

the shipyard workers, which is equivalent to the

natural background level experienced in areas of the

mountain states in the U.S., has been suggested.

Randomized controlled trials are probably more common

in medicine than in epidemiology, as they are very

commonly used to evaluate medications and nutrients.

They are best done double-blind, as mentioned before,

to prevent 'placebo' biases.

~Ruth 2 aka Ruth Sponsler

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