Biostatistics

184 CHAPTER 6 ESTIMATION
with lumbar spondylolysis were treated surgically with the technique. The following table gives the
Japanese Orthopaedic Association (JOA) evaluation score for lower back pain syndrome for men and
women prior to the surgery. The lower score indicates less pain.
Gender
JOA scores
Female 14, 13, 24, 21, 20, 21
Male 21, 26, 24, 24, 22, 23, 18, 24, 13, 22, 25, 23, 21, 25
Source: Satoshi Nozawa, Katsuji Shimizu, Kei Miyamoto, and Mizuo
Tanaka, “Repair of Pars Interarticularis Defect by Segmental Wire
Fixation in Young Athletes with Spondylolysis,” American Journal of
Sports Medicine, 31 (2003), 359–364.
6.4.5. Krantz et al. (A-12) investigated dose-related effects of methadone in subjects with torsade
de pointes, a polymorphic ventricular tachycardia. In the study of 17 subjects, nine were being
treated with methadone for opiate dependency and eight for chronic pain. The mean daily
dose of methadone in the opiate dependency group was 541 mg/day with a standard deviation of
156, while the chronic pain group received a mean dose of 269 mg/day with a standard deviation
of 316.
6.4.6. Transverse diameter measurements on the hearts of adult males and females gave the following
results:
Group Sample Size x (cm) s (cm)
Males 12 13.21 1.05
Females 9 11.00 1.01
Assume normally distributed populations with equal variances.
6.4.7. Twenty-four experimental animals with vitamin D deficiency were divided equally into two groups.
Group 1 received treatment consisting of a diet that provided vitamin D. The second group was not
treated. At the end of the experimental period, serum calcium determinations were made with the
following results:
Treated group: x ¼ 11:1mg=100 ml; s ¼ 1:5
Untreated group: x ¼ 7:8mg=100 ml; s ¼ 2:0
Assume normally distributed populations with equal variances.
6.4.8. Two groups of children were given visual acuity tests. Group 1 was composed of 11 children who
receive their health care from private physicians. The mean score for this group was 26 with a
standard deviation of 5. Group 2 was composed of 14 children who receive their health care from the
health department, and had an average score of 21 with a standard deviation of 6. Assume normally
distributed populations with equal variances.
6.4.9. The average length of stay of a sample of 20 patients discharged from a general hospital was 7 days
with a standard deviation of 2 days. A sample of 24 patients discharged from a chronic disease
hospital had an average length of stay of 36 days with a standard deviation of 10 days. Assume
normally distributed populations with unequal variances.
6.4.10. In a study of factors thought to be responsible for the adverse effects of smoking on human
reproduction, cadmium level determinations (nanograms per gram) were made on placenta tissue of a