BMJ study question

[JOHN.RICH@sargentlundy.com]

Radsafers,

Could someone please give me a little help on the statistics?

Is the "multivariate odds ratio" the equivalent of a correlation?  AND if

it is, are values of 0.47 and 0.59 strong or weak correlations?   If the

"multivariate odds ratio" is something else, can someone explain its

significance?



Thanx much in advance - -- john rich







>From the paper:



BMJ  2004;328:19 (3 January),

"Effect of low doses of ionising radiation in infancy

on cognitive function in adulthood: Swedish population

based cohort study,"



Per Hall, Hans-Olov Adami, Dimitrios Trichopoulos,

Nancy L Pedersen, Pagona Lagiou, Anders Ekbom,

professor1, Martin Ingvar, Marie Lundell, and Fredrik

Granath



RESULTS: The proportion of boys who attended high

school decreased with increasing doses of radiation to

both the frontal and the posterior parts of the brain

from about 32% among those not exposed to around 17%

in those who received > 250 mGy. For the frontal dose,

the multivariate odds ratio was 0.47 (95% confidence

interval 0.26 to 0.85, P for trend 0.0003) and for the

posterior dose it was 0.59 (0.23 to 1.47, 0.0005). A

negative dose-response relation was also evident for

the three cognitive tests for learning ability and

logical reasoning but not for the test of spatial

recognition.



CONCLUSIONS: Low doses of ionising radiation to the

brain in infancy influence cognitive abilities in

adulthood.







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