1. Intro to Stats and Collecting Data

Which of the following statements is true about a $\mathrm{population}$ in a statistical survey?

Body Temperature The given expression is used for determining the likelihood that the average (mean) human body temperature is different from the value of 98.6°F that is commonly used. Find the given value and round the result to two decimal places.

(98.2 - 98.6) / (0.62 / sqrt(106) )

"Determine whether the data are qualitative or quantitative. Explain your reasoning.

Distances of track events"

Treatment for Osteoporosis Osteoporosis is a condition in which people experience decreased bone mass and an increase in the risk of bone fracture. Actonel is a drug that helps combat osteoporosis in postmenopausal women. In clinical trials, 1374 postmenopausal women were randomly divided into experimental and control groups. The subjects in the experimental group were administered 5 milligrams (mg) of Actonel, while the subjects in the control group were administered a placebo. The number of women who experienced a bone fracture over the course of one year was recorded. Of the 696 women in the experimental group, 27 experienced a fracture during the course of the year. Of the 678 women in the control group, 49 experienced a fracture during the course of the year.  

b. The experiment was double-blind. What does this mean?  

"[NW] Chew Your Food Researchers wanted to determine the association between number of times one chews food and food consumption. They identified 45 individuals who were 18 to 45 years of age. First, the researchers determined a baseline for number of chews before swallowing food. Next, each participant attended three sessions to eat pizza for lunch until comfortably full by chewing each portion of food 100%, 150%, and 200% of their baseline number of chews before swallowing. Food intake for each of the three chewing treatments was then measured. It was found that food consumption was reduced significantly, by 9.5% and 14.8%, respectively, for the 150% and 200% number of chews compared to the baseline. Source: Yong Zhu and James H. Hollis. “Increasing the Number of Chews before Swallowing Reduces Meal Size in Normal-Weight, Overweight, and Obese Adults,” Journal of the Academy of Nutrition and Dietetics, 11 November 2013.

How is control used in this study?"

State Populations Currently, California has the largest population with 39,776,830 residents, and Wyoming has the smallest population with 573,520 residents.

a. Are the population sizes of the different states discrete or continuous?

Energy Consumption. Exercises 1–4 refer to the amounts of energy consumed in the author’s home. (Most of the data are real, but some are fabricated.) Each value represents energy consumed (kWh) in a two-month period. Let each subgroup consist of the six amounts within the same year. Data are available for download at www.TriolaStats.com.

Energy Consumption: R Chart Let each subgroup consist of the 6 values within a year. Construct an R chart and determine whether the process variation is within statistical control. If it is not, identify which of the three out-of-control criteria lead to rejection of statistically stable variation.

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Highway Strength The New York State Department of Transportation evaluated the quality of the New York State Thruway by testing core samples collected at regular intervals of 1 mile.

Researchers Katherine Tucker and associates wanted to determine whether consumption of cola is associated with lower bone mineral density. They looked at 1125 men and 1413 women in the Framingham Osteoporosis Study, which is a cohort that began in 1971. The first examination in this study began between 1971 and 1975, with participants returning for an examination every 4 years. Based on results of questionnaires, the researchers were able to determine cola consumption on a weekly basis. Analysis of the results indicated that women who consumed at least one cola per day (on average) had a bone mineral density that was significantly lower at the femoral neck than those who consumed less than one cola per day. The researchers did not find this relation in men.

Why is this a cohort study?

"Alcohol Dependence To determine if topiramate is a safe and effective treatment for alcohol dependence, researchers conducted a 14-week trial of 371 men and women aged 18 to 65 years diagnosed with alcohol dependence. In this double-blind, randomized, placebo-controlled experiment, subjects were randomly given either 300 milligrams (mg) of topiramate (183 subjects) or a placebo (188 subjects) daily, along with a weekly compliance enhancement intervention. The variable used to determine the effectiveness of the treatment was self-reported percentage of heavy drinking days. Results indicated that topiramate was more effective than placebo at reducing the percentage of heavy drinking days. The researchers concluded that topiramate is a promising treatment for alcohol dependence. Source: Bankole A. Johnson, Norman Rosenthal, et al. “Topiramate for Treating Alcohol Dependence: A Randomized Controlled Trial,” Journal of the American Medical Association, 298(14):1641–1651, 2007.

What does it mean for the experiment to be double-blind? Why do you think it is necessary for the experiment to be double-blind?"

"School Psychology A school psychologist wants to test the effectiveness of a new method for teaching reading. She recruits 500 first-grade students in District 203 and randomly divides them into two groups. Group 1 is taught by means of the new method, while group 2 is taught by traditional methods. The same teacher is assigned to teach both groups. At the end of the year, an achievement test is administered and the results of the two groups are compared.

Explain how time of day the course is taught could potentially confound the results of the study. Can anything be done to eliminate the effect of this confounding variable?"

In Exercises 9–20, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

Reported and Observed Results A Harris Interactive study involved 1013 adults who were interviewed about washing their hands in restrooms and another 6336 adults who were observed in public restrooms.

Given the data set: $4$, $7$, $7$, $10$, $12$, what is the median of the data?

Which type of data have elements in common but do not fit into rigid rows and columns in a table?

Which of the following best describes the purpose of inferential statistics in an introductory statistics course?