gives the distribution of socioeconomic status. Test to prove that there is
a significant association between the mother’s age and preterm delivery;
that the poorer the mother, the more likely the preterm delivery. State
your null hypothesis and choice of test size.6.27 Postneonatal mortality due to respiratory illnesses is known to be in-
versely related to maternal age, but the role of young motherhood as a
risk factor for respiratory morbidity in infants has not been explored
thoroughly. A study was conducted in Tucson, Arizona aimed at the
incidence of lower respiratory tract illnesses during the first year of life.
In this study, over 1200 infants were enrolled at birth between 1980 and
- The data shown in Table E6.27 are concerned with wheezing lower
respiratory tract illnesses (wheezing LRIs). For each of the two groups,
boys and girls, test to investigate the relationship between maternal age
and respiratory illness. State clearly your null and alternative hypotheses
and choice of test size.
TABLE E6.27
Boys Girls
Maternal Age (years) No Yes No Yes
< 21 19 8 20 7
21–25 98 40 128 36
26–30 160 45 148 42
> 30 110 20 116 256.28 Data were collected from 2197 white ovarian cancer patients and 8893
white controls in 12 di¤erent U.S. case–control studies conducted by
various investigators in the period 1956–1986. These were used to eval-
uate the relationship of invasive epithelial ovarian cancer to reproductive
TABLE E6.28a
Cases Controls
Duration of unprotected
intercourse (years)
< 2 237 477
2–9 166 354
10–14 47 91
b 15 133 174
History of infertility
No 526 966
Yes
No drug use 76 124
Drug use 20 11244 COMPARISON OF POPULATION PROPORTIONS