A study was conducted to demonstrate that soy beans inoculated with nitrogen-fixing bacteria yield more and grow adequately without expensive environmentally deleterious synthesized fertilizers. The trial was conducted under controlled conditions with uniform amounts of soil. The initial hypothesis was that inoculated plants would outperform their uninoculated counterparts. This assumption is based on the facts that plants need nitrogen to manufacture vital proteins and amino acids and that nitrogen-fixing bacteria would make more of this substance available to plants, increasing their size and yield. There were 8 inoculated plants (I) and 8 uninoculated plants (U). The plant yield as measured by pod weight for each plant is given in Table 2.20.
What is your overall impression concerning the pod weight in the two groups?
Want to see the full answer?
Check out a sample textbook solutionChapter 2 Solutions
WebAssign for Rosner's Fundamentals of Biostatistics, 8th Edition [Instant Access], Single-Term
- Researchers are interested in testing the effectiveness of a new immunosuppressive therapy to be used post-transplant to reduce graft failure in the host. Suppose researchers investigating this new therapy are concerned about the dangerous side-effects of the drug. For instance, participants that would like to enroll in the study are not allowed to already have diabetes, as the immunosuppressive agent has been found to drastically increase fasting glucose levels, which could be very dangerous for diabetics. This means, however, that participants that enter and are treated with the new drug may develop diabetes as time goes on. Suppose the following table addresses the incidence of diabetes in the study depending on treatment group. (α=.01) Type II Diabetes No Type II Diabetes Total Investigational Drug 45 32 77 Best standard of Care 35 50 85 Total 80 82 162 Based on this information complete the hypothesis steps for Chi-Squared below:…arrow_forwardPatients immobilized for a substantial amount of time can develop deep vein thrombosis (DVT), a blood clot in a leg or pelvis vein. DVT can have serious adverse health effects and can be difficult to diagnose. On its website, drug manufacturer Pfizer reports the outcome of a study looking at the effectiveness of the drug Fragmin (dalteparin) in preventing DVT in immobilized patients. Of the 1518 randomly chosen immobilized patients given Fragmin, 42 experienced a complication from DVT. Of the 1473 randomly chosen immobilized patients given a placebo, 73 experienced a complication from DVT. Compute the proportion (risk) of patients experiencing DVT complications for immobilized patients treated with Fragmin. (Enter the proportion with 4 decimal places. DO NOT enter the percent.)arrow_forwardPeople continue to convert forests into farmland with deleterious ecological and climatic impacts. Some countries have shifted from net deforestation to net reforestation. One of the arms of this study intents to show that returning farmland to a more diverse and natural environment can greatly increase soil carbon, and in consequence pump carbon out to the atmosphere. In order to test this hypothesis, 17 plots of 1 hectare were selected throughout New York, New Jersey and Pennsylvania Farmers owning the land received compensation for the loss of income when income was lost. The 17 plots were randomized into the control group, Y1 (farmer continue normal farming methods) or a polyculture of maple, birch, spruce, oak, and beech was planted, Y2. After 10 years of culture, the amount of soil carbon was measured as 91= 6.01 Mg/ha s1= .93 n1=9 and 92=.75MG/ha s2=1.24 n2=8. Shapiro Wilks test for Y1 pvalue = 0.12 and Y2 pvalue = 0.07. Given that data, does afforestation (planting of forest…arrow_forward
- There have been many studies recently concerning coffee drinking and cholesterol level. While it is known that several coffee-bean components can elevate blood cholesterol level, it is thought that a new type of paper coffee filter may reduce the presence of some of these components in coffee. The effect of the new filter on cholesterol level will be studied over a 10-week period using 300 nonsmokers who each drink 4 cups of caffeinated coffee per day. Each of these 300 participants will be assigned to one of two groups: the experimental group, who will only drink coffee that has been made with the new filter, or the control group, who will only drink coffee that has been made with the standard filter. Each participant’s cholesterol level will be measured at the beginning and at the end of the study. Which test would you conduct to determine whether the change in cholesterol level would be greater if people used the new filter rather than using the standard filter? Why would the…arrow_forwardThere have been many studies recently concerning coffee drinking and cholesterol level. While it is known that several coffee-bean components can elevate blood cholesterol level, it is thought that a new type of paper coffee filter may reduce the presence of some of these components in coffee. The effect of the new filter on cholesterol level will be studied over a 10-week period using 300 nonsmokers who each drink 4 cups of caffeinated coffee per day. Each of these 300 participants will be assigned to one of two groups: the experimental group, who will only drink coffee that has been made with the new filter, or the control group, who will only drink coffee that has been made with the standard filter. Each participant’s cholesterol level will be measured at the beginning and at the end of the study. Describe an appropriate method for assigning the subjects to the two groups so that each group will have an equal number of subjects. In this study, the researchers chose to include a…arrow_forwardDue to the increasing number of customers, MTAKUJA commercial Bank located at the University of Dar es Salaam has been facing the problem of long customers' queues since the beginning of this year. The Branch manager decided to conduct a small study to determine the cause of this problem. The study concluded that most of its bank tellers were slow and less efficient. However, the study recommended that the long queues would decrease substantially if at least two of its three banks tellers are operating efficiently. Therefore, to solve this problem the bank came up with the new policy that each bank taller should process at least 25 customers per hour. The probability that the first, second and third bank tellers will fail to comply with the new policy is 0.12, 0.09 and 0.1 respectively. Assume that the three counters at MTAKUJA bank operate independent of each other, find the probability that the queues will decrease substantially.arrow_forward
- Researchers have noted a decline in cognitive functioning as people age (Bartus, 1990). However, the results from other research suggest that the antioxidant in foods such as blueberries can reduce and even reverse those age-related declines, at least in laboratory rats (Joseph,et al.,1999). Based on these results, one might theorize that the same antioxidants might benefit elderly humans. Suppose a researcher is interested in testing this theory. The researcher obtains a sample of n = 16 adults who are older than 65, and gives and gives each participant a daily dose of blueberry supplement that is very high in antioxidants. After taking the supplement for 6 months, the participants are given a standardized cognitive skills test and produce a mean score of M = 50.2. For the general population of elderly adults scores on the test average μ =45 and form a normal distribution with a σ = 9. Can the researchers conclude that the supplement significantly increases cognitive skills? Use a…arrow_forwardIn warm and humid parts of the world, a constant battle is waged against termites. Scientists have discovered that certain tree resins are deadly to termites, and thus the trees producing these resins become a valuable crop. In one experiment typical of the type used to test the protective power of a resin, two doses of resin (5 mg and 10 mg) were dissolved in a solvent and placed on filter paper. Five dishes were prepared with filter paper at dose level 5 mg and five with filter paper at dose level 10 mg. Twenty-five termites were then placed in each dish to feed on the filter paper. At the end of 15 days, the number of surviving termites was counted. The results are shown below. You may assume that the number of surviving termites is approximately normal for each group. Dose 5mg (Group 1): 8, 11, 7, 9, 11Dose 10mg (Group 2): 2, 0, 1, 16, 13 Unless otherwise stated, give your answers to three decimal places. Construct a 90% confidence interval for the difference in average surviving…arrow_forwardReducing scrap of 4-foot planks of hardwood is an important factor in reducing cost at a wood-flooring manufacturing company. Accordingly, engineers at Lumberworks are investigating a potential new cutting method involving lateral sawing that may reduce the scrap rate. To examine its viability, samples of 600 and 500 planks, respectively, were examined under the old and new methods. Sixty-one of the 600 planks were scrapped under the old method, whereas 36 of the 500 planks were scrapped under the new method. (You may find it useful to reference the appropriate table: z table or t table)a. Construct the 99% confidence interval for the difference between the population scrap rates between the old and new methods, respectively. (Negative values should be indicated by a minus sign. Round intermediate calculations to at least 4 decimal places and final answers to 2 decimal places.)arrow_forward
- It has been shown that the fertilizer magnesium ammonium phosphate, Mg, NH4PO4, is an effective supplier of the nutrients necessary for plant growth. A study was conducted at George Mason University to determine a possible optimum level of fertilization, based on the enhanced vertical growth response of the chrysanthemums. Forty chrysanthemum seedlings were divided into four groups, each containing 10 plants. Each was planted in a similar pot containing a uniform growth medium. To each group of plants an increasing concentration of Mg,NH4PO4, measured in grams per bushel, was added: 50 g/bu, 100 g/bu, 200 g/bu, and 400g/bu. The sample means for each group was 15.34 cm, 17.16 cm, 18.3 cm, and 20.1 cm, respectively. Here SST = 758.035. (a) Construct the ANOVA table. (b) Use the Bonferroni correction to construct all g pairwise confidence intervals with t a df 2.792. What is a? 3arrow_forwardReducing scrap of 4-foot planks of hardwood is an important factor in reducing cost at a wood-flooring manufacturing company. Accordingly, engineers at Lumberworks are investigating a potential new cutting method involving lateral sawing that may reduce the scrap rate. To examine its viability, samples of 600 and 500 planks, respectively, were examined under the old and new methods. Sixty-two of the 600 planks were scrapped under the old method, whereas 34 of the 500 planks were scrapped under the new method. (You may find it useful to reference the appropriate table: z table or t table) a. Construct the 90% confidence interval for the difference between the population scrap rates between the old and new methods, respectively. (Negative values should be indicated by a minus sign. Round intermediate calculations to at least 4 decimal places and final answers to 2 decimal places.) Confidence interval is I to %. 論arrow_forwardReducing scrap of 4-foot planks of hardwood is an important factor in reducing cost at a wood-flooring manufacturing company. Accordingly, engineers at Lumberworks are investigating a potential new cutting method involving lateral sawing that may reduce the scrap rate. To examine its viability, samples of 500 and 400 planks, respectively, were examined under the old and new methods. Sixty-two of the 500 planks were scrapped under the old method, whereas 36 of the 400 planks were scrapped under the new method. (You may find it useful to reference the appropriate table: z table or ttable) a. Construct the 95% confidence interval for the difference between the population scrap rates between the old and new methods, respectively. Report the lower and the upper limits as proportions. (Negative value should be indicated by a minus sign. Round final answers to 2 decimal places.) Confidence interval is to b. Select the null and alternative hypotheses to test for differences in the population…arrow_forward
- MATLAB: An Introduction with ApplicationsStatisticsISBN:9781119256830Author:Amos GilatPublisher:John Wiley & Sons IncProbability and Statistics for Engineering and th...StatisticsISBN:9781305251809Author:Jay L. DevorePublisher:Cengage LearningStatistics for The Behavioral Sciences (MindTap C...StatisticsISBN:9781305504912Author:Frederick J Gravetter, Larry B. WallnauPublisher:Cengage Learning
- Elementary Statistics: Picturing the World (7th E...StatisticsISBN:9780134683416Author:Ron Larson, Betsy FarberPublisher:PEARSONThe Basic Practice of StatisticsStatisticsISBN:9781319042578Author:David S. Moore, William I. Notz, Michael A. FlignerPublisher:W. H. FreemanIntroduction to the Practice of StatisticsStatisticsISBN:9781319013387Author:David S. Moore, George P. McCabe, Bruce A. CraigPublisher:W. H. Freeman