A study sought to demonstrate that soy beans inoculated with nitrogen-fixing bacteria yield more and grow adequately without the use of 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 was based on the fact that plants need nitrogen to manufacture vital proteins and amino acids and that nitrogenfixing 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 8.28.
Table 8.28 Pod weight (g) from inoculated (I) and uninoculated (U) plantsa
aThe data for this problem were supplied by David Rosner.
What test can be used to compare the mean pod weight between the two groups?
Want to see the full answer?
Check out a sample textbook solutionChapter 8 Solutions
Fundamentals of Biostatistics
- Suppose a researcher is interested inthe effectiveness in a new childhood exercise program implemented in a SRS of schools across a particular county. In order to test the hypothesis that the new program decreases BMI (Kg/m2), the researcher takes a SRS of children from schools where the program is employed and a SRS from schools that do not employ the program and compares the results. Assume the following table represents the SRSs of students and their BMIs. Student intervention group BMI (kg/m2) Student control group BMI (kg/m2) A 18.6 A 21.6 B 18.2 B 18.9 C 19.5 C 19.4 D 18.9 D 22.6 E 24.1 F 23.6 A) Assuming that all the necessary conditions are met (normality, independence, etc.) carry out the appropriate statistical test to determine if the new exercise program is effective. Use an alpha level of 0.05. Do not assume equal variances.B) Construct a 95% confidence interval about your estimate for the average difference in BMI between the groups.arrow_forwardA new chemotherapy drug is released to treat leukemia and researchers suspect that the drug may have fewer side effects than the most commonly used drug to treat leukemia. The two drugs have equivalent efficacy. In order to determine if a larger study should be conducted to look into the prevalence of side effects for the two drugs, set up a Mann-Whitney Utest at the alpha equals .05 level and interpret its results. Number of Reported Side-Effects Old Drug 0 1 3 3 5 New Drug 0 0 1 2 4 Old Drug New Drug Total Sample (Ordered Smallest to Largest) Ranks Old Drug New Drug Old Drug New Drug A) We fail to reject H0, which…arrow_forward. A new chemotherapy drug is released to treat leukemia and researchers suspect that the drug may have fewer side effects than the most commonly used drug to treat leukemia. The two drugs have equivalent efficacy. In order to determine if a larger study should be conducted to look into the prevalence of side effects for the two drugs, set up a Mann-Whitney U test at the alpha equals .05 level and interpret its results. Number of Reported Side-EffectsOld Drug 0 1 1 3 5New Drug 0 0 1 2 4 Old Drug New Drug Total Sample(Ordered Smallest to Largest) RanksOld Drug New Drug Old Drug New DrugR1= R2= A) We reject H0 in favor of H1, which states the two populations are not equal at the alpha equals .05 level because the calculated U value of 10 is greater than the critical U value of 2.B) We reject H0 in favor of H1, which states the two populations are not equal at the alpha equals .05 level because the calculated U value of 8.5 is greater than the critical U value of 2.C) We fail to reject H0,…arrow_forward
- Researchers interested in lead exposure due to car exhaust sampled the blood of 52 police officers subjected to constant inhalation of automobile exhaust fumes while working traffic enforcement in a primarily urban environment. The blood samples of these officers had an average lead concentration of 124.32 µg/l and an SD of 37.74 µg/l; a previous study of individuals from a nearby suburb, with no history of exposure, found an average blood level concentration of 35 µg/l. Write down the hypotheses that would be appropriate for testing if the police officers appear to have been exposed to a higher concentration of lead. Explicitly state and check all conditions necessary for inference on these data. Test the hypothesis that the downtown police officers have a higher lead exposure than the group in the previous study. Interpret your results in context. Based on your preceding result, without performing a calculation, would a 99% confidence interval for the average blood concentration…arrow_forwardIn terms of the model parameters, state the null hypothesis that, after controlling for sales and roe, ros has no effect on CEO salary. State the alternative that better stock market performance increases a CEO’s salary.arrow_forwardA new chemotherapy drug is released to treat leukemia and researchers suspect that the drug may have fewer side effects than the most commonly used drug to treat leukemia. The two drugs have equivalent efficacy. In order to determine if a larger study should be conducted to look into the prevalence of side effects for the two drugs, set up a Mann-Whitney U test at the alpha equals .05 level and interpret its results. Number of Reported Side-Effects Old Drug 0 1 3 3 5 New Drug 0 0 1 2 4 A) We fail to reject H0, which states the two populations are equal at the alpha equals .05 level because the calculated Uvalue of 16.5 is greater than the critical U value of 2. B) We fail to reject H0, which states the two populations are equal at the alpha equals .05 level because the calculated Uvalue of 8.5 is greater than the critical U value of 2. C) We reject H0 in favor of H1, which…arrow_forward
- A test of body reaction to the Malaysian citizens who have taken their vaccine was conducted. Selected citizens who got side effect are categorised according to their blood type and the type of vaccine received. From a sample of 250 citizens, 150 of them were administered with Sinovac while the rest received AstraZeneca. Table 4 shows the number of citizens who had side effect after being vaccinated. Type of vaccine Blood type A B AB O Sinovac 50 M 50 20 AstraZeneca 30 20 20 N Does different blood type among people who had side effect relate to the type of vaccinereceived at A=0.025?arrow_forwardA study was conducted to assess the impact of nutrient enrichment on zooplankton densities in A & B Islands. An ecologist sampled populations of zooplankton in these two locations and observed the nutrient enrichment level was higher in A island when compared with the level in B island. It is predicted the zooplankton densities in A island will be greater than those found in B island.arrow_forwardRed Wine and Weight LossResveratrol, a compound in grapes and red wine, has been shown to promote weight loss in rodents and now in a primate.1 Lemurs fed a resveratrol supplement for four weeks had decreased food intake, increased metabolic rate, and a reduction in seasonal body-mass gain compared to a control group. Suppose a hypothetical study is done for a different primate species, with one group given a resveratrol supplement and the other group given a placebo. We wish to see if there is evidence that resveratrol increases the mean metabolism rate for this species. (This exercise presents hypothetical data. We will see the results from the actual study later in this chapter.) (a) State the null and alternative hypotheses.Let group 1 be the species taking a resveratrol supplement and let group 2 be the species taking a placebo.arrow_forward
- A new chemotherapy drug is released to treat leukemia and researchers suspect thst the drug may have fewer side effects than the most commonly used drug to treat leukemia. The two drugs have equivalent efficacy. In order to determine if a larger study should be conducted to look into the prevalence of side effects for the two drugs, set up a Mann-Whitney U test at the alpha equals .05 level and interpret its results. Number of reported side effects Old drug 0 1 3 3 5 New drug 0 0 1 2 4arrow_forwardDrinking This Much Coffee Each Day May Lead to Brain Shrinkage and Increase Dementia Risk More than 7 in 10 Americans drink coffee daily, averaging about three cups per day, according to the National Coffee Association. At that rate (and at the right time of day, AKA not too close to bedtime), coffee acts as a pick-me-up that offers a surprisingly wide range of health benefits. But new research published June 2021 in the journal Nutritional Neuroscience proves that—like with most things in life—there can be too much of a good thing. After diving into 8 to 12 years of data collected about the coffee habits of more than 398,000 adults enrolled in a British study, the Australian research team discovered that sipping more than six cups of coffee per day was associated with a 53% increased risk of dementia and a smaller brain volume. So while coffee can be good to give you a little energy buzz, it can be not so great for your brain health—if you consume it in large quantities. Those who…arrow_forward. A new chemotherapy drug is released to treat leukemia and researchers suspect that the drug may have fewer side effects than the most commonly used drug to treat leukemia. The two drugs have equivalent efficacy. In order to determine if a larger study should be conducted to look into the prevalence of side effects for the two drugs, set up a Mann-Whitney U test at the alpha equals .05 level and interpret its results. Number of Reported Side-Effects Old Drug 0 1 3 3 5 New Drug 0 0 1 2 4 Old Drug New Drug Total Sample (Ordered Smallest to Largest) Ranks Old Drug New Drug Old Drug New Drug 0 0 0 0 2 2 1 0 1 0 4.5 2 3 1 3 1 7.5 4.5 3 2 3 2 7.5 6 5 4 5 4 10 9 Total R1=31.5 R2=23.5 A) We…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