Concept explainers
Dexamethasone and IQ. In the paper “Outcomes at School Age After Postnatal Dexamethasone Therapy for Lung Disease of Prematurity” (New England Journal of Medicine, Vol. 350, No. 13, pp. 1304–1313), T. Yeh et al. studied the outcomes at school age in children who had participated in a double-blind, placebo-controlled trial of early postnatal dexamethasone therapy for the prevention of chronic lung disease of prematurity. All of the infants in the study had had severe respiratory distress syndrome requiring mechanical ventilation shortly after birth. On the WeissStats site, we provide the school-age IQs of the 74 children in the control group, based on the study results. Use the technology of your choice to do the following.
- a. Obtain a normal
probability plot, boxplot, histogram, and stem-and-leaf diagram of the data. - b. Based on your results from part (a), can you reasonably apply one-standard-deviation χ2-procedures to the data? Explain your reasoning.
- c. Overall, IQs of school-age children have a standard deviation of 16. At the 1% significance level, do the data provide sufficient evidence to conclude that IQs of school-age children in similar postnatal circumstances as those in the control group of this study have a smaller standard deviation than that of school-age children in general?
- d. Find and interpret a 99% confidence interval for the standard deviation of IQs of all school-age children in similar postnatal circumstances as those in the control group of this study.
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Introductory Statistics (10th Edition)
- A pathological video game user (PVGU) is a video game user that averages 31 or more hours a week of gameplay. According to the article “Pathological Video Game Use among Youths: A Two-Year Longitudinal Study” (Pediatrics, Vol. 127, No. 2, pp. 319–329) by D. Gentile et al., in 2011, about 9% of children in grades 3–8 were PVGUs. Suppose that, today, five youths in grades 3–8 are randomly selected. Let X represent the number of youths who are PVGUs. Calculate the probability that EXACTLY three youths are PVGUsarrow_forwardNCI Cancer Bulletin, December 2, 2008 Volume 5 / Number 24 Title of the article: After Menopause, Weight Affects Breast Cancer Rates More than Mammography Use Women who are overweight or obese after menopause face an increased risk of breast cancer, but a large prospective cohort study indicates that the frequency of mammography use and screening accuracy are not the primary explanations for higher rates of breast cancer in these women. The same is true of large, invasive breast cancer tumors and advanced stage disease; risk increases with weight, but higher rates are not explained by the frequency or accuracy of screening mammography before breast cancer was diagnosed. The study appears in the December 3 Journal of the National Cancer Institute. Dr. Karla Kerlikowske of the San Francisco Veterans Affairs Medical Center and colleagues gathered data on 287,115 postmenopausal women who were registered in the Breast Cancer Surveillance Consortium database. Reflecting a trend in the…arrow_forwardNCI Cancer Bulletin, December 2, 2008 Volume 5 / Number 24 Title of the article: After Menopause, Weight Affects Breast Cancer Rates More than Mammography Use Women who are overweight or obese after menopause face an increased risk of breast cancer, but a large prospective cohort study indicates that the frequency of mammography use and screening accuracy are not the primary explanations for higher rates of breast cancer in these women. The same is true of large, invasive breast cancer tumors and advanced stage disease; risk increases with weight, but higher rates are not explained by the frequency or accuracy of screening mammography before breast cancer was diagnosed. The study appears in the December 3 Journal of the National Cancer Institute. Dr. Karla Kerlikowske of the San Francisco Veterans Affairs Medical Center and colleagues gathered data on 287,115 postmenopausal women who were registered in the Breast Cancer Surveillance Consortium database. Reflecting a trend in the…arrow_forward
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