EBK FUNDAMENTALS OF BIOSTATISTICS
8th Edition
ISBN: 9781305465510
Author: Rosner
Publisher: YUZU
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Dark Chocolate for Good Health
A study¹ examines chocolate's effects on blood vessel function in healthy people. In the randomized, double-blind, placebo-controlled
study, 11 people received 46 grams (1.6 ounces) of dark chocolate (which is naturally flavonoid-rich) every day for two weeks, while a
control group of 10 people received a placebo consisting of dark chocolate with low flavonoid content. Participants had their vascular
health measured (by means of flow-mediated dilation) before and after the two-week study. The increase over the two-week period
was measured, with larger numbers indicating greater vascular health. For the group getting the good dark chocolate, the mean
increase was 1.3 with a standard deviation of 2.32, while the control group had a mean change of -0.96 with a standard deviation of
1.58.
¹Engler, M., et. al., "Flavonoid-rich dark chocolate improves endothelial function and increases plasma epicatechin concentrations in
healthy adults," Journal of the…
"Does ginkgo improve memory?" The law allows marketers of herbs and other natural substances
to make health claims that are not supported by evidence. Brands of ginkgo extract claim to "improve memory
and concentration." A randomized experiment found some statistically significant evidence for such effects.
The subjects were 250 healthy volunteers over 65 years old. They were randomly assigned to take ginkgo or a
placebo pill (a dummy pill that looks and tastes the same). All the subjects took a battery of tests for learning
and memory before treatment started and again after six weeks.
a). The article said the study was double-blind. What does this mean in the context of this study? Be very
specific on who's being blinded and explain why they should be blinded.
b). You suspect physical fitness and mental fitness go hand-in-hand. Create a flow chart to describe a design
for an experiment to include the confounding variable physical fitness. Be very specific in your design.
Include all…
Calcium and Blood Pressure Does increasing the amount of calcium in our diet reduce blood
pressure? Examination of a large sample of people revealed a relationship between calcium intake
and blood pressure. Such observational studies do not establish causation. Researchers therefore
designed a randomized comparative experiment.
The subjects were 21 healthy men who volunteered to take part in the experiment. They were
randomly assigned to two groups: 10 of the men received a calcium supplement for 12 weeks,
while the control group of 11 men received a placebo pill that looked identical. The experiment
was double-blind. The response variable is the decrease in systolic (top number) blood pressure
for a subject after 12 weeks, in millimeters of mercury. An increase appears as a negative number.
Do the data provide convincing evidence that a calcium supplement reduces blood pressure more
than a placebo, on average, for subjects like the ones in this study?
Group 1 (calcium)
Group (placebo)…
Chapter 12 Solutions
EBK FUNDAMENTALS OF BIOSTATISTICS
Ch. 12 - Nutrition Researchers compared protein intake...Ch. 12 - Nutrition Researchers compared protein intake...Ch. 12 - Prob. 3PCh. 12 - Prob. 4PCh. 12 - Prob. 5PCh. 12 - Pulmonary Disease Twenty-two young asthmatic...Ch. 12 - Pulmonary Disease Twenty-two young asthmatic...Ch. 12 - Prob. 8PCh. 12 - Prob. 32PCh. 12 - Gastroenterology In Table 12.39, we present data...
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- What is an experiment?arrow_forwardWhat is meant by the sample space of an experiment?arrow_forwardA study was conducted [15] concerning the effect of calcium supplementation on bone loss among postmenopausal women. Women were randomized to (1) estrogen cream and calcium placebo (n = 15), (2) placebo estrogen cream and 2000 mg/day of calcium (n = 15), or (3) placebo estrogen cream and calcium placebo (n = 13). Subjects were seen every 3 months for a 2-year period. The rate of bone loss was computed for each woman and expressed as a percentage of the initial bone mass. The results are shown in Table 12.36 12.31 What test can be used to compare the mean rate of bone loss in the three groups?12.32 Implement the test in Problem 12.31, and report a p-value.12.33 Identify which pairs of groups are different from each other, using both t tests and the method of multiple comparisons. Report a p-value for each pair of treatment groups.12.34 Which methodology do you think is more appropriate in Problem 12.33?arrow_forward
- A study was conducted [15] concerning the effect of calcium supplementation on bone loss among postmenopausal women. Women were randomized to (1) estrogen cream and calcium placebo (n = 15), (2) placebo estrogen cream and 2000 mg/day of calcium (n = 15), or (3) placebo estrogen cream and calcium placebo (n = 13). Subjects were seen every 3 months for a 2-year period. The rate of bone loss was computed for each woman and expressed as a percentage of the initial bone mass. The results are shown in Table 12.36 12.34 Which methodology do you think is more appropriate in Problem 12.33? the subparts have been solved 1 hour or more agoarrow_forwardMental Health A study was performed looking at the effect of physical activity on cognitive function among adults at high risk for Alzheimer's disease. There were 170 eligible subjects randomly assigned to either an exercise intervention (exercise group) or a control intervention (control group). The subjects were followed at 6-month intervals up to 18 months of follow-up. The primary assessment scale was the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog). The results at 18 months of follow-up among participants with mild cognitive impairment are given in the table below. (Let population 1 be the exercise group and population 2 be the control group. Use exercise group control group.) Mean difference from baseline (18-month score minus baseline score) among participants with mild cognitive impairment in the ADAS-Cog score* Mean change 95% CI n H₁: Exercise group Control group USE SALT -0.37 (-1.37, 0.63) 48 -0.43 (-1.35, 0.49) 52 (a) What is the standard deviation of…arrow_forwardCurrent Attempt in Progress Dark Chocolate for Good Health A study examines chocolate's effects on blood vessel function in healthy people. In the randomized, double-blind, placebo- controlled study, 11 people received 46 grams (1.6 ounces) of dark chocolate (which is naturally flavonoid-rich) every day for two weeks, while a control group of 10 people received a placebo consisting of dark chocolate with low flavonoid content. Participants had their vascular health measured (by means of flow-mediated dilation) before and after the two-week study. The increase over the two-week period was measured, with larger numbers indicating greater vascular health. For the group getting the good dark chocolate, the mean increase was 1.3 with a standard deviation of 2.32, while the control group had a mean change of-0.96 with a. standard deviation of 1.58. "Engler, M., et. al., "Flavonoid-rich dark chocolate improves endothelial function and increases plasma epicatechin concentrations in healthy…arrow_forward
- A study was made of 1,057 cases of poisoning in children treated as inpatients at Milwaukee Children's Hospital from 1962 through 1968. Data on date of occurrence, age and sex of the child, and type of agent involved were recorded and analyzed by standard statistical methods. Poisoning was due to ingestion of aspirin in 35 per cent of the children studied and to the ingestion of hydrocarbon distillates in 18 per cent. A statistically significant male dominance was found for ingestion of hydrocarbons; age-specific peaks were found for some categories. Trends as to the relative and absolute frequencies of each specific poison from one year to the next were noted; possible reasons for increasing or decreasing trends are discussed. Is this study descriptive or inferential? Explain your answer. What are the variables used in the study? In your opinion, what level of measurement was used to obtain the data from the variables? Does the article define the population? If so, how is it…arrow_forwardDoes heavy cell phone use affect brain activity? There is some concern about possible negative effects of radiofrequency signals delivered to the brain. In a randomized matched-pairs study, 47 healthy participants had cell phones placed on the left and right ears. Brain glucose metabolism (a measure of brain activity) was measured for all participants under two conditions: with one cell phone turned on for 50 minutes (the “on” condition) and with both cell phones off (the “off” condition). The amplitude of radio frequency waves emitted by the cell phones during the “on” condition was also measured. Is this an example of “paired-samples” or “independent samples”? The investigators were interested in seeing whether average brain glucose metabolism was different based on whether the cell phones were turned on or off. State the null and alternative hypotheses for this test. Suppose that the mean of differences ? is 0.8, ignoring the unit for now, and the standard deviation of the…arrow_forwardBased on the results presented, did the exercise intervention groups still receive a health benefit even if significant weight loss did not occur? Explain.arrow_forward
- Kava is a beverage or extract that is made from Piper methysticum, a plant native to the western Pacific islands. Suppose that, in a randomized comparative experiment to determine if taking kava daily can reduce insomnia, a group of participants with insomnia were randomly assigned to take kava (treatment group) or a placebo (control group). After six weeks, the participants were interviewed to see if they experienced a decrease in insomnia. The table shows the results from the sample. The counts are the number of people in each group who experienced a decrease in insomnia. Group Description Population proportion Sample size Sample count Sample proportion 1 Treatment (kava) P1 n₁ = 402 x1 = 213 P₁ = 0.5299 2 Control (placebo) P2 n₂ = 521 x₂ = 121 P2 = 0.2322 Compute the standard error estimate, SE, of the difference in the sample proportions. Give your answer to at least four decimal places. 0.0438 SE = Incorrect Determine the value of the two-sample z-statistic for the difference in…arrow_forwardDoes ginkgo improve memory? The law allows marketers of herbs and other natural substances to make health claims that are not supported by evidence. Brands of ginkgo extract claim to “improve memory and concentration.” A randomized comparative experiment found no statistically significant evidence for such effects. The subjects were 350 healthy volunteers over 60 years old. They were randomly assigned to ginkgo or a placebo pill (a dummy pill that looks and tastes the same). All the subjects took a battery of tests for learning and memory before treatment started and again after six weeks. (a) The study was double-blind. Why is this important? (b) Can the results of this study be generalized to a larger population? Can cause-and-effect be inferred? Explain. (c) Explain why it is advantageous to use 350 volunteers in this study, rather than, say, 30.arrow_forwardAn experiment was conducted for better understanding of the effectiveness of a particular type of drug for reducing bad cholesterol (LDL) level. The purpose of the experiment was to determine whether different dosages used have significant different outcomes in average LDL reduction. Twenty subjects with LDL at around 250 to 300 mg/dL had participated in the study and were randomly divided into four groups. Each group was given a specific level of dosage of the drug each day for one month, with a control group that only provided with placebo. The reduction in LDL was recorded and showed in the following table. Positive number indicates reduction and negative numbers indicates increasing in DLD. Use statistical software to analyze the data and answer the following question. Control Light Dosage Level Medium Dosage Level Heavy Dosage Level 7 25 73 81 -3 17 60 71 6 22 55 79 5 21 41 60 15 12 36 85 Perform a One-way…arrow_forward
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