A general practice based study sought to find out if people’s ears increase
in size as they get older.
206 patients were studied with ear size being assessed by the length of
the left external ear from the top to the lowest part.
Measurements were made simply, using a transparent plastic ruler.
The relation between the patient’s age and ear length (see graph below)
was examined by calculating a regression equation.
The mean age of the patients was 53.75 years (range 30 - 93) and the mean ear length was 67.5 mm (range 52.0 - 84.0 mm). The linear regression equation was
ear length = 55.9 + 0.22 × age
with the 95% confidence interval for the b coefficient being 0.17 to 0.27. The author concluded that ‘It seems therefore that as we get older our ears get bigger (on average by 0.22 mm a year)’ (Heathcote 1995)
In a study of physical fitness and cardiovascular risk factors in children, blood pressure and recovery index (post exercise recovery rate, an indicator of fitness) were measured (Hoffman and Walter 1989). Multiple regression was used to look at the relationship between systolic blood pressure and recovery index, adjusted for age, race, area of residence and ponderal index (wt/ht2). For the boys, the adjusted regression coefficient of systolic blood pressure on recovery index was given as follows: b = –0.086, SE(b) = 0.039, 95% CI = –0.162 to –0.010.
Heathcote, J.A. (1995) Why do old men have big ears? British Medical Journal 311, 1668.
Hofman, A. and Walter, H.J. (1989) The association between physical fitness and cardiovascular disease risk factors in children in a five-year follow-up study. International Journal of Epidemiology 18, 830-5.
Questions from Martin Bland and Janet Peacock: Statistical Questions in Evidence-based Medicine, Oxford University Press, Oxford, 2000.
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