In an experiment, if persons are assigned randomly to experimental and control groups, then the samples are considered?
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In an experiment, if persons are assigned randomly to experimental and control groups, then the samples are considered?
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- A coffee shop gets its stock of bagels for the day delivered from a baker in the morning before opening. Suppose they need to sell 250 bagels every day to break even on their purchase of bagels from the baker. The store manager, when closing the store for the night, notices that many bagels are left unsold and fears they are not breaking even. Rather than using anecdotes, the store manager decides to collect some data. 42 days are randomly sampled and the number of bagels sold in that day is measured. The sample mean is found to be 240 bagels with a standard deviation of 30 bagels. Are they losing money selling bagels? Let μ be the true number of bagels sold in a day. Test this at claim at the α= 0.01 level. (a) Set up the null and alternative hypothesis (using mathematical notation/numbers AND interpret them in context of the problem) (b) Calculate the test statistic (c) Calculate the critical valueIn a large clinical trial, 399,911 children were randomly assigned to two groups. The treatment group consisted of 199,160 children given a vaccine for a certain disease, and 35 of those children developed the disease. The other 200,751 children were given a placebo, and 134 of those children developed the disease. Consider the vaccine treatment group to be the first sample. Identify the values of n, , p4, 9,, n,, p,, 92, p, and q. n1 =A coffee shop gets its stock of bagels for the day delivered from a baker in the morning before opening. Suppose they need to sell 250 bagels every day to break even on their purchase of bagels from the baker. The store manager, when closing the store for the night, notices that many bagels are left unsold and fears they are not breaking even. Rather than using anecdotes, the store manager decides to collect some data. 42 days are randomly sampled and the number of bagels sold on that day is measured. The sample mean is found to be 240 bagels with a standard deviation of 30 bagels. Are they losing money selling bagels? Let μ be the true number of bagels sold in a day. Test this at claim at theα= 0.01 level. (a) Set up the null and alternative hypothesis (using mathematical notation/numbers AND interpret them in the context of the problem) (b) Calculate the test statistic (c) Calculate the critical value (d) Draw a picture of the distribution of the test statistic underH0. Label and…
- When an experiment has a completely randomized design, a. experimental units are randomly assigned to each combination of levels of two factors. b. independent, random samples of experimental units are assigned to the treatments. c. the randomization occurs only within blocks.Researchers studying starfish collected two independent random samples of 40 starfish. One sample came from an ocean area in the north, and the other sample came from an ocean area in the south. Of the 40 starfish from the north, 6 were found to be over 8 inches in length. Of the 40 starfish from the south, 11 were found to be over 8 inches in length. Which of the following is the test statistic for the appropriate test to investigate whether there is a difference in proportion of starfish over 8 inches in length in the two ocean areas (north minus south) ? 6−11640+1140√ A 6−110.1540+0.27540√ B 0.15−0.275(0.15)(0.275)(140+140)√ C 0.15−0.275(0.2125)(0.7875)(140+140)√ D 0.15−0.275(0.2125)(0.7875)140+140√In a large clinical trial, 401,602 children were randomly assigned to two groups. The treatment group consisted of 201,876 children given a vaccine for a certain disease, and 27 of those children developed the disease. The other 199,726 children were given a placebo, and 108 of those children developed the disease. Consider the vaccine treatment group to be the first sample. Identify the values of n₁. P₁. 9₁. 0₂. P2. 42. P. and q. A
- In a random sample of 400 electrical components, 88 are found to be defective. You wish to test the null hypothesis that the population proportion of defective components is 20% versus the alternative hypothesis that the population proportion is not 20%.You choose a significant level of 5%. What is your statistical decision in this case?Athabasca Fishing Lodge is located on Lake Athabasca in northern Canada. In one of its recent brochures, the lodge advertises that 75% of its guests catch northern pike over 20 pounds. Suppose that last summer 65 out of a random sample of 84 guests did, in fact, catch northern pike weighing over 20 pounds. Does this indicate that the population proportion of guests who catch pike over 20 pounds is different from 75% (either higher or lower)? Use? = 0.05 . Is the sample size large enough to approximate distribution using Normal distribution? WHY?.b. What are the hypotheses?A marketing agency wanted to determine if a new commercial changed people's opinion about a company. They recruited n=30 participants to watch the commercial. First, everyone was givien a survey to determine their attitudes toward the company. Then, everyone watched the new commercial. Finally, they were given the same survey again and asked about their attitudes toward the comapny after seeing the commercial. The agency wanted to see if attitudes were changed by the commercial. What statistical test should they use?
- Give an example of a study for which the one sample z-test would the appropriate test statistic to use.In a study, a large sample representative of the households in the US were asked about their smoking habits. The data suggested that current smokers were on average much healthier than those who recently stopped smoking. Investigators concluded that smoking does not necessarily lead to worse health outcomes. Consider the following statements. Select the ones you agree with, based on the information given. Group of answer choices A.In a randomized experiment, smoker and non-smoker groups are similar across all potential characteristics. b.The conclusions were justified by the data. c.This is an observational study. d.This study is a randomized controlled experiment. e.The results can be explained due to confounding. Current smokers are different from those who recently stopped in ways that are related to health outcomes.Based upon the output provided, what is sample size?
