Results of Scottish study may be due to confounding with ageBMJ 1996; 313 doi: https://doi.org/10.1136/bmj.313.7048.44b (Published 06 July 1996) Cite this as: BMJ 1996;313:44
- Gillian Raab
- Professor Applied Statistics Research Group, Mathematics Department, Napier University, Edinburgh EH11 4BN
EDITOR,—In their paper analysing the sperm quality of a sample of Scottish men Stewart Irvine and colleagues show an association between birth cohort and sperm numbers and concentrations.1 This univariate association is interpreted as a deterioration of semen quality with later year of birth. The authors …
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