Concept explainers
It is commonplace to gain weight after quitting smoking. To determine the effectiveness of the drug Naltrexone in limiting weight gain after quitting smoking, 147 subjects who smoked 20 or more cigarettes daily were randomly divided into two groups. All 147 subjects received a 21-milligram (mg) transdermal nicotine patch (to curb nicotine cravings while trying to quit smoking). However, seventy-two subjects received a placebo, while 75 received 25 mg of Naltrexone. After 6 weeks, the placebo subjects had a
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Fundamentals of Statistics (5th Edition)
- A researcher wanted to determine if using an octane booster would increase gasoline mileage. A random sample of seven cars was selected; the cars were driven for two weeks without the booster and two weeks with the booster.arrow_forwardA drug trial had 161 participants. A survey was done to gather information about the participants’ experiences with side effects. The table below gives the results for two possible side effects.arrow_forwardOver a 4-month period, among 30 people with bipolar disorder, patients who were given a high dose (10 g/day) of omega-3 fats from fish oil improved more than those given a placebo. This experiment involved a control group of subjects who received a placebo. Why didn't the experimenters just give everyone the omega-3 fats to see if they improved? Choose the correct answer below. O A. They need to avoid confounding the participants. O B. They need to compare omega-3 results to something. O C. They need to conserve omega-3 fats. O D. They need to blind the participants.arrow_forward
- Researchers wanted to know the effectiveness of a new anti-venom shot. A study was conducted on 245 children who had nonlethal scorpion stings. The ages of the children ranged from 6 months to 18 years old. Each child was randomly assigned to receive a shot of the anti-venom or a placebo shot. Researchers recorded whether or not their condition improved over the next four hours. They found that about 73% of the children who were given anti-venom saw an improvement in their condition whereas only about 23% of the children who were given the placebo saw an improvement in their condition. Identify the population.The population is all children 6 months to 18 years old with nonlethal scorpion stings. Identify the sample.The sample is 245 children 6 months to 18 years old with nonlethal scorpion stings. What is the treatment variable? The treatment variable is the anti-venom shot. What is the response (or outcome) variable?The outcome variable is improvements in their condition.…arrow_forwardIn the article “Explaining an Unusual Allergy,” appearing on the Everyday Health Network, Dr. A. Feldweg explained that allergy to sulfites is usually seen in patients with asthma. The typical reaction is a sudden increase in asthma symptoms after eating a food containing sulfites. Studies are performed to estimate the percentage of the nation’s 10 million asthmatics who are allergic to sulfites. In one survey, 38 of 500 randomly selected U.S. asthmatics were found to be allergic to sulfites. Find and interpret a 95% confidence interval for the proportion p of all U.S. asthmatics who are allergic to sulfites.arrow_forwardA county environmental agency suspects that the fish in a particular polluted lake have elevated mercury levels. To confirm that suspicion, five striped basses in that lake were caught and their tissues were tested for mercury. For the purpose of comparison, four striped basses in an unpolluted lake were also caught and tested. The fish tissue mercury levels in mg/kg are given below. Sample I(From Polluted Lake) 0.523 0.723 0.523 0.623 0.523 Sample II(From Unpolluted Lake) 0.323 0.223 0.523 0.323 0.000 (a) Construct the 95% confidence interval for the difference in the population means based on these data. (b) Test, at the 5% level of significance, whether the data provide sufficient evidence to conclude that fish in the polluted lake have elevated levels of mercury in their tissue.arrow_forward
- In a study conducted by the U.S. Department of Health and Human Services, a sample of 546 boys aged 6–11 was weighed, and it was determined that 87 of them were overweight. A sample of 508 girls aged 6–11 was also weighed, and 74 of them were overweight. Can you conclude that the proportion of boys who are overweight differs from the proportion of girls who are overweight?arrow_forwardA food-frequency questionnaire is used to measure dietary intake. The respondent specifies the number of servings of various food items they consumed over the previous week. The dietary cholesterol is then quantified for each respondent. The researchers were interested in assessing if there was an association between dietary cholesterol intake and high blood pressure. In a large sample of individuals who had completed the questionnaire, 250 persons with a high dietary cholesterol intake (greater than 300 mg /day) were selected and 250 persons with a low dietary cholesterol intake (less than 300 mg/day) were selected. The 500 selected participants had their medical history taken and were classified as having normal or high blood pressure. The data are given here. Dietary Cholesterol Blood Pressure Total High Low High 159 91 250 Low 78 172 250 Total 237 263 500 Test 2: two-tailed test for comparing two independent proportions Clearly state…arrow_forwardResearchers studied 208 infants whose brains were temporarily deprived of oxygen due to complications at birth. When researchers detected oxygen deprivation, they randomly assigned babies to either usual care or to a whole-body cooling group. The goal was to see whether reducing body temperature for three days after birth increased the rate of survival without brain damage. What is the explanatory variable? A. Survival without brain damage B.Infants whose brains are temporarily deprived of oxygen C. Usual care or whole-body coolingarrow_forward
- A food-frequency questionnaire is used to measure dietary intake. The respondent specifies the number of servings of various food items they consumed over the previous week. The dietary cholesterol is then quantified for each respondent. The researchers were interested in assessing if there was an association between dietary cholesterol intake and high blood pressure. In a large sample of individuals who had completed the questionnaire, 250 persons with a high dietary cholesterol intake (greater than 300 mg /day) were selected and 250 persons with a low dietary cholesterol intake (less than 300 mg/day) were selected. The 500 selected participants had their medical history taken and were classified as having normal or high blood pressure. The data are given here. Dietary Cholesterol Blood Pressure Total High Low High 159 91 250 Low 78 172 250 Total 237 263 500 Two hypothesis tests can be used to answer this research problem. Test 1:…arrow_forwardA group of 500 children who suffer from asthma were asked to participate in a study to determine the effectiveness of a new medication. The patients were randomly divided into two groups: one that was given the actual medication and one that received a placebo. The results of the study are below. What percentage of patients who took the medication had improved symptoms? Symptoms improved Symptoms did not improve Medication Placebo 205 65 140 90 O 65.2% O 75.9% O 41% O 54%arrow_forwardA study questioned 387 women receiving free bone mineral density screening. The questions focused on past smoking history. Subjects undergoing hormone replacement therapy (HRT), and subjects not undergoing HRT, were asked if they had ever been a regular smoker. In the HRT group, 29.3 percent of 220 women stated that they were at some point in their life a regular smoker. In the non–HRT group, 17.3 percent of 106 women responded positively to being at some point in their life a regular smoker. Sixty-one women chose not to answer the question. Construct a 95% confidence interval for the difference in smoking percentages for the two populations of women represented by the subjects in the study. What is the standard error of the difference in proportions?arrow_forward
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