Examine the results of a study1 investigating whether fast food consumption increases one’s concentration of phthalates, an ingredient in plastics which has been linked to multiple health problems including hormone disruption. The study included 8877 people who recorded all the food they ate over a 24-hour period and then provided a urine sample. Two specific phthalate byproducts were measured (in ng/mL) in the urine: DEHP and DiNP. Find a 95% confidence interval for the difference, μF-μN, in mean concentration between people who have eaten fast food in the last 24 hours and those who haven’t. The mean concentration of DEHP in the 3095 participants who had eaten fast food was x¯F=83.6 with sF=194.7 while the mean for the 5782 participants who had not eaten fast food was x¯N=59.1 with sN=152.1. Round your answers to one decimal place. The 95% confidence interval is to .

2.      The city council is considering a law that would ban concealed weapons in all public facilities. A sample has been selected from the community and surveyed about support for the proposed ordinance. Is there a statistically significant relationship between age and support for the law against carrying concealed weapons (use p=.05, χ2(critical) = 3.841)? Use the five step model as a guide and write a sentence or two interpreting your results.                        Age       Under 40 40 and older   Support       For 142   77 219   Against 106 170 276     248 247 495

NCI 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…

A study published by Babcock and Marks (2010) showed that the average full-time U.S. college student studied for μ = 14 hours per week (SD = 4.8 hours per week) in 2005. We want to know if this average has changed in the past 15 years. In other words, we are going to do a study in which we try to determine whether there has been an impact of the passage of time on the amount of time college students spend studying. We selected a sample of n = 64 of today’s college students and find that they spent an average of M = 12.5 hours per week studying. Does this sample indicate a significant change in the number of hours spent studying? Use a two-tailed test (this means non-directional hypothesis) with α = .05.