Table E1.37 gives the percentages of current smokers by age for two
study areas.
(a) Display the age distribution for Lawrenceville by means of a pie
chart.
(b)Display the age distribution for South Hills by means of a pie chart.
How does this chart compare to the one in part (a)?
(c) Display the smoking rates for Lawrenceville and South Hills, side by
side, by means of a bar chart.1.38 Prematurity, which ranks as the major cause of neonatal morbidity and
mortality, has traditionally been defined on the basis of a birth weight
under 2500 g. But this definition encompasses two distinct types of
infants: infants who are small because they are born early, and infants
who are born at or near term but are small because their growth was
retarded.Prematurity has now been replaced bylow birth weightto
describe the second type, andpreterm to characterize the first type
(babies born before 37 weeks of gestation).
A case–control study of the epidemiology of preterm delivery was
undertaken at Yale–New Haven Hospital in Connecticut during 1977.
The study population consisted of 175 mothers of singleton preterm
infants and 303 mothers of singleton full-term infants. Tables E1.38a
and E1.38bgive the distribution of age and socioeconomic status.
TABLE E1.38a
Age Cases Controls
14–17 15 16
18–19 22 25
20–24 47 62
25–29 56 122
b 30 35 78TABLE E1.38b
Socioeconomic Level Cases Controls
Upper 11 40
Upper middle 14 45
Middle 33 64
Lower middle 59 91
Lower 53 58
Unknown 5 5(a) Refer to the age data and choose the ‘‘b30’’ group as the baseline.
Calculate the odds ratio associated with every other age group. Is it
true, in general, that the younger the mother, the higher the risk?EXERCISES 51