Phase I of a Clinical Trial A clinical test on humans of a new drug is normally done in three phases. Phase I is conducted with a relatively small number of healthy volunteers. For example, a phase I test of bexarotene involved only 14 subjects. Assume that we want to treat 14 healthy humans with this new drug and we have 16 suitable volunteers available.
a. If the subjects are selected and treated one at a time in sequence, how many different sequential arrangements are possible if 14 people are selected from the 16 that are available?
b. If 14 subjects are selected from the 16 that are available, and the 14 selected subjects are all treated at the same time, how many different treatment groups are possible?
c. If 14 subjects are randomly selected and treated at the same time, what is the
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Chapter 4 Solutions
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- Urban Travel Times Population of cities and driving times are related, as shown in the accompanying table, which shows the 1960 population N, in thousands, for several cities, together with the average time T, in minutes, sent by residents driving to work. City Population N Driving time T Los Angeles 6489 16.8 Pittsburgh 1804 12.6 Washington 1808 14.3 Hutchinson 38 6.1 Nashville 347 10.8 Tallahassee 48 7.3 An analysis of these data, along with data from 17 other cities in the United States and Canada, led to a power model of average driving time as a function of population. a Construct a power model of driving time in minutes as a function of population measured in thousands b Is average driving time in Pittsburgh more or less than would be expected from its population? c If you wish to move to a smaller city to reduce your average driving time to work by 25, how much smaller should the city be?arrow_forward1. Suppose that, in Example 2.27, 400 units of food A, 600 units of B, and 600 units of C are placed in the test tube each day and the data on daily food consumption by the bacteria (in units per day) are as shown in Table 2.6. How many bacteria of each strain can coexist in the test tube and consume all of the food? Table 2.6 Bacteria Strain I Bacteria Strain II Bacteria Strain III Food A 1 2 0 Food B 2 1 1 Food C 1 1 2arrow_forwardCustomer Preference Two movie theatres that show several different movies each night compete for the same audience. Of the people who attend theatre A one night, 10 will attend again the next night and 5 will attend Theatre B the next night. Of the people who attend Theatre B one night, 8 will attend again the next night and 6 will attend Theatre A the next night. Of the people who attend neither theatre one night, 3 will attend Theatre A the next night and 4 will attend Theatre B the next night. Find and interpret the steady state matrix for this situation.arrow_forward
- Do lizards play a role in spreading plant seeds? Some research carried out in a country would suggest so. The researchers collected 400 seeds of this particular type of fig, 100 of which were from each treatment: lizard dung, bird dung, rock hyrax dung, and uneaten figs. They planted these seeds in batches of 5, and for each group of 5 they recorded how many of the seeds germinated. This resulted in 20 observations for each treatment. The treatment means and standard deviations are given in the accompanying table. Treatment n Uneaten figs 20 | 2.80 0.30 Lizard dung 20 2.75 0.36 Bird dung 20 2.10 0.35 Hyrax dung 20 1.85 0.29 n USE SALT (a) Construct the appropriate ANOVA table, and test the hypothesis that there is no difference between the means for the number of seeds germinating for the four treatments. (Use a = 0.05. Round your mean squares to three decimal places and F statistic to two decimal places.) Source of Variation Sum of Squares Mean df F Square Treatments 3 13.45 4.483333…arrow_forwardDo lizards play a role in spreading plant seeds? Some research carried out in a country would suggest so. The researchers collected 400 seeds of this particular type of fig, 100 of which were from each treatment: lizard dung, bird dung, rock hyrax dung, and uneaten figs. They planted these seeds in batches of 5, and for each group of 5 they recorded how many of the seeds germinated. This resulted in 20 observations for each treatment. The treatment means and standard deviations are given in the accompanying table. Treatment x S Uneaten figs 20 2.80 0.30 Lizard dung 20 2.75 0.36 Bird dung 20 2.10 0.35 Hyrax dung 20 1.85 0.29 USE SALT (a) Construct the appropriate ANOVA table, and test the hypothesis that there is no difference between the means for the number of seeds germinating for the four treatments. (Use a = 0.05. Round your mean squares to three decimal places and F statistic to two decimal places.) Source of df Sum of Squares Mean Square F Variation Treatments Error Total Use…arrow_forwardDo lizards play a role in spreading plant seeds? Some research carried out in South Africa would suggest so. Researchers on a study collected 400 seeds of a particular type of fig, 100 of which were from each treatment: lizard dung, bird dung, rock hyrax dung, and uneaten figs. They planted these seeds in batches of 5, and for each group of 5 they recorded how many of the seeds germinated. This resulted in 20 observations for each treatment. The treatment means and standard deviations are given in the accompanying table. Treatment n x s Uneaten figs 20 2.50 0.30 Lizard dung 20 2.30 0.33 Bird dung 20 1.70 0.34 Hyrax dung 20 1.45 0.28 (a) Construct the appropriate ANOVA table. (Use technology. Round your answers to three decimal places.) Source ofvariation Degrees offreedom Sum ofsquares Meansquares F Ratio F Prob Between Groups Within Group Total 79 Test the hypothesis that there is no difference between mean number of seeds…arrow_forward
- Do lizards play a role in spreading plant seeds? Some research carried out in South Africa would suggest so. Researchers on a study collected 400 seeds of a particular type of fig, 100 of which were from each treatment: lizard dung, bird dung, rock hyrax dung, and uneaten figs. They planted these seeds in batches of 5, and for each group of 5 they recorded how many of the seeds germinated. This resulted in 20 observations for each treatment. The treatment means and standard deviations are given in the accompanying table. Treatment Uneaten figs 20 2.50 0.29 Lizard dung 20 2.40 0.32 Bird dung 20 1.80 0.35 Hyrax dung 20 1.40 0.29 (a) Construct the appropriate ANOVA table. (Use technology. Round your answers to three decimal places.) Degrees of freedom Source of Sum of Mean F Ratio F Prob variation squares squares Between Groups Within Group Total 79 Test the hypothesis that there is no difference between mean number of seeds germinating for the four treatments. (Use a significance level…arrow_forwardA pharmaceutical company conducts an experiment to test the effect of a new cholesterol medication. The company selects 15 subjects randomly from a larger population. Each subject is randomly assigned to one of three treatment groups. Within each treament group, subjects receive a different dose of the new medication. In Group 1, subjects receive 0 mg/day; in Group 2, 50 mg/day; and in Group 3, 100 mg/day. What test would you use?arrow_forwardA pharmaceutical company conducts an experiment to test the effect of a new cholesterol medication. The company selects 15 subjects randomly from a larger population. Each subject is randomly assigned to one of three treatment groups. Within each treatment group, subjects receive a different dose of the new medication. In Group 1, subjects receive 0 mg/day; in Group 2, 50 mg/day; and in Group 3, 100 mg/day. After 30 days, doctors measure the cholesterol level of each subject. The results for all 15 subjects appear in the table below: Dosage Group 1 Group 2 Group 3 O mg 50 mg 100 mg 210 210 180 240 240 210 270 250 220 270 270 210 300 270 240 (a) Perform an appropriate test to test whether there are differences among the mean cholesterol level by three different doses of the new medication at 5% level of significance. (b) Compute the p-value and indicate whether it leads to the same conclusion.arrow_forward
- Here is one way in which nature regulates the size of animal populations: high population dehslty attracts predators, which remove a higher proportion of the population than when the density of the prey is low. One study looked at kelp perch and their common predator, the kelp bass. On each of four occasions, the researcher set up four large circular pens on sandy ocean bottoms off the coast of southern California. He randomly assigned young perch to 1 of 4 pens so that one pen had 10 perch, one pen had 20 perch, one pen had 40 perch and the final pen had 60 perch. then he dropped the nets protecting the pens, allowing bass to swarm in, and counted the number of perch killed after two hours. A regression analysis was performed on the 16 data points using x = number of perch in pen and y = proportion of perch killed. Here is a residual plot and a histogram of the residuals. 0,4 - 0.3 0.2 0.1- 0.0 -0.1 - -0.2- -0.3 - -0.4 10 20 30 40 50 60 Number of perch Starnes & Tabor, The Practice of…arrow_forwardA random sample of 1000 people with known allergies to poison ivy participated in a recent study. Oil from the poison ivy plant was rubbed on a patch of skin. For 500 of the subjects, the oil it was washed off within 5 minutes. For the other 500 subjects, the oil was washed off after 5 minutes. Observed reactions were recorded as "none," "mild," or "strong." The results are summarized in the following table. Reaction Within 5 Minutes After 5 Minutes Row Total NoneMildStrong 4055144 6833894 473389138 Column Total 500 500 1000 Suppose a person selected at random from this sample of 1000 subjects. What is the probability that a strong reaction was observed, given that the oil was washed off within 5 minutes? (Select below). 0.188 0.044 0.088 0.319arrow_forwardA random sample of 1000 people with known allergies to poison ivy participated in a recent study. Oil from the poison ivy plant was rubbed on a patch of skin. For 500 of the subjects, the oil it was washed off within 5 minutes. For the other 500 subjects, the oil was washed off after 5 minutes. Observed reactions were recorded as "none," "mild," or "strong." The results are summarized in the following table. Reaction Within 5 Minutes After 5 Minutes Row Total NoneMildStrong 4056530 48326126 453391156 Column Total 500 500 1000 Suppose a person selected at random from this sample of 1000 subjects. What is the probability that a strong reaction was observed, given that the oil was washed off within 5 minutes?arrow_forward
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