Concept explainers
A carcinogenicity study was conducted to examine the tumor potential of a drug product scheduled for initial testing in humans. A total of 300 rats (150 males and 150 females) was studied for a 6-month period. At the beginning of the study, 100 rats (50 males. 50 females) were randomly assigned to the control group. 1(H) (50 males. 50 females) to the low-dose group, and the remaining 100 (50 males, 50 females) to the high-dose group. On each day of the 6-month period, the rats in the control group received an injection of an inert solution, whereas those in the drug groups received an injection of the solution plus drug. The sample data are shown in the accompanying table.
- a. Conduct a test of whether there is a significant difference in the proportions of rats having one or more tumors for the three treatment groups with α = .05.
- b. Does there appear to be a drug-related problem regarding tumors for this drug product? That is, as the dose is increased, does there appear to be an increase in the proportion of rats with tumors?
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Chapter 10 Solutions
An Introduction to Statistical Methods and Data Analysis
- In the initial test of the Salk vaccine for polio, 400,000 children were selected and divided into two groups of 200,000. One group was vaccinated with the Salk vaccine while the second group was vaccinated with a placebo. Of those vaccinated with the Salk vaccine, 33 later developed polio. Of those receiving the placebo, 115 later developed polio. Test the hypothesis that the Salk vaccine is effective in lowering the polio rate. Use a=0.01 Apply p-value and classical approach. Show step1-ste03.arrow_forwardAn experiment to determine if a migraine medication decreases a person's average number of monthly migraines is performed on 400 people who report they have several migraines a month. Researchers randomly assigned 200 people to the treatment group and 200 people to the control group. After the study, the researchers determined that 48 of the subjects in the treatment group and 28 of the subjects in the control group average fewer migraines per month. The data from the two groups are resampled 150 times, and the table shows the distribution of the differences of the proportions for the reconfigured treatment and control groups.arrow_forwardElizon Pharmaceuticals, Inc., announced the results of its first human trial of NPI 32101, a topical form of its skin ointment. A total of 225 patients diagnosed with skin irritations were randomly divided into three groups as part of a double-blind, placebo-controlled study to test the effectiveness of the new topical cream. The first group received a 0.5% cream, the second group received a 1.0% cream, and the third group received a placebo. Groups were treated twice daily for a 6-week period. (a)What type of experimental design is this? (b)What is the control group for this study? (c)What is the factor that is set to predetermined levels? What is the treatment? (d)What does it mean for this study to be double-blind? (e)Identify the experimental units. (f)Draw a diagram to illustrate the design.arrow_forward
- In a study of hypnotic suggestion, 16 male volunteers were randomly allocated to a treatment groupand a control group. Each subject participated in a two-phase experimental session. In the first phase, respiration was measured while the subject was awake and at rest. In the second phase, the subject was told to imagine that he was performing muscular work, and respiration was measured again. For subjects in the treatment group, hypnosis was induced between the first and second phases; thus, the suggestion to imagine muscular work was “hypnotic suggestion” for treatment subjects and “waking suggestion” for control subjects. The table below shows the measurements of total ventilation (liters of air per minute per square meter of body area) for all 16 subjects. (a) For those being hypnotized (treatment group), test the hypotheses H0: μrest = μwork versus Ha:μrest 6= μwork, where μrest and μwork are respectively the mean total ventilation when they are atrest and when they are performing…arrow_forwardLet p1 and p2 be the respective proportions of women with iron-deficiency anemia in each of two developing countries. A random sample of 1900 women from the first country yielded 513 women with iron-deficiency anemia, and an independently chosen, random sample of 1700 women from the second country yielded 515 women with iron-deficiency anemia. Can we conclude, at the 0.10 level of significance, that the proportion of women with anemia in the first country is less than the proportion of women with anemia in the second country? Perform a one-tailed test. Then complete the parts below.Carry your intermediate computations to three or more decimal places and round your answers as specified in the parts below. a. State the null hypothesis H0 and the alternative hypothesis H1. b. Find the values of the test statistic. c. FInd the p-value. d. Can we conclude that the proportion of women with anemia in the first country is less than the proportion of women with anemia in the second country?arrow_forwardA double-blind randomized experiment compared the effects of the drug Lorcaserin and a placebo on weight loss in overweight adults. All subjects were also required to undergo diet and exercise counseling. The study involved 1000 participants where half of them would take Lorcaserin and half the placebo. The researchers found that after a year the treatment group had an average weight loss of 5.8 kg while the placebo group had an average weight loss of 3.9 carmona, kg. Based on this information researchers need to decide if Locarserin can be a possible treatment for weight loss. a. What would be a Type I error in this context? Your answer should consist of both the researchers’ decision and what the reality is. b. What would be a Type II error in this context? Your answer should consist of both the researchers’ decision and what the reality is.arrow_forward
- In a study of chromosomal anomalies observed in a randomly selected sample of 1200 infertile men with either a zero or low sperm count, a team of researchers assigned the value of 1 for the presence of any chromosomal anomaly in the subject's sperm and the value of 0 for the absence of all chromosomal anomalies in the subject's sperm.Of the 600 men with zero sperm count, 48 had chromosomal anomalies. Of the 600 men with low sperm count, 15 had chromosomal anomalies. The researchers would like to test the hypothesesHo: P1 = P2Ha: P1 does not equal P2where p₁ the true proportion of all men with zero sperm count that have chromosomal anomalies and p₂ = the true proportion of all men with low sperm count that have chromosomal anomalies.What is the z standardized test statistic, for this test?arrow_forwardThe contingency table shows the result of a random sample of students by Ziyi Zhang at PCC and the number of hours they spend investing on Robinhood and Acorns by age and gender. At alpha =0.05, can you conclude that age is related to gender when it comes to time spent investing on Robinhood and Acorns. GENDER 16-20yrs 21-30yrs 31-40yrs 41-50yrs 51-60yrs 61yrs or older Male 45 170 90 72 45 26 Female 9 30 21 17 10 5 What is the Chi-square test statistics and the decision for this question. The Test statistics is . Leave your answer in 3 decimal places. DECISION: We the null hypothesis.arrow_forwardTwenty middle-aged men with glucose readings between 90 milligrams per deciliter and 120 milligrams per deciliter of blood were selected randomly from the population of similar male patients at a large local hospital. Ten of the 20 men were assigned randomly to group A and received a placebo. The other 10 men were assigned to group B and received a new glucose drug. After two months, posttreatment glucose readings were taken for all 20 men and were compared with pretreatment readings. The reduction in glucose level (Pretreatment reading − Posttreatment reading) for each man in the study is shown here. Group A (placebo) reduction (in milligrams per deciliter): 12, 8, 17, 7, 20, 2, 5, 9, 12, 6 Group B (glucose drug) reduction (in milligrams per deciliter): 29, 31, 13, 19, 21, 5, 24, 12, 8, 21 Part A: Do the data provide convincing evidence, at the α = 0.02 level, that the glucose drug is effective in producing a reduction in mean glucose level? Part B: Create and interpret a 98%…arrow_forward
- A study conducted by researchers was designed "to determine if application of duct tape is as effective as cryotherapy in the treatment of common warts." The researchers randomly divided 6969 patients into two groups. The 3535 patients in group 1 had their warts treated by applying duct tape. The 3434 patients in group 2 had their warts treated by cryotherapy. Once the treatments were complete, it was determined that 6969% of the patients in group 1 and 8585% of the patients in group 2 had complete resolution of their warts. The researchers concluded that cryotherapycryotherapy is significantly more effective in treating warts than duct tapeduct tape. Complete parts (a) through (d) below.(a) What is the research objective? A.To determine if duct tape is as effective as cryotherapy in the treatment of warts B.To determine if cryotherapy is as effective as duct tape in the treatment of warts C.To determine if cryotherapy is effective in the treatment of warts D.To determine if…arrow_forwardHormone Therapy and Dementia. An issue of Science News (Vol. 163, No. 22, pp. 341–342) reported that the Women’s Health Initiative cast doubts on the benefit of hormone-replacement therapy. Researchers randomly divided 4532 healthy women over the age of 65 years into two groups. One group, consisting of 2229 women, received hormone-replacement therapy; the other group, consisting of 2303 women, received placebo. Over 5 years, 40 of the women receiving the hormone-replacement therapy were diagnosed with dementia, compared with 21 of those getting placebo. a. At the 5% significance level, do the data provide sufficient evidence to conclude that healthy women over 65 years old who take hormone-replacement therapy are at greater risk for dementia than those who do not? b. Determine and interpret a 90% confidence interval for the difference in dementia risk rates for healthy women over 65 years old who take hormone-replacement therapy and those who do not.arrow_forwardA magazine reported on the "... treatment-emergent adverse events that occurred in 2% or more patients treated with a new medicine and with incidence greater than placebo in the treatment of depression, OCD, or bulimia." In the study, patients took the new medicine and patients were given placebo. Identify the a. treatment group, b. control group, and c. treatments.arrow_forward
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGAL