A group of educators want to determine how effective tutoring is in raising students’ grades in a math class, so they arrange free tutoring for those who want it. Then they compare final exam grades for the group that took advantage of the tutoring and the group that did not. Suppose the group participating in the tutoring tended to receive higher grades on the exam. Does that show that the tutoring worked? If not, explain why not and suggest a confounding variable.
Answer to relevant QuestionsA doctor who believes strongly that antidepressants work better than "talk therapy" tests depressed patients by treating half of them with antidepressants and the other half with talk therapy. After six months the patients ...A study by Pezzoli and Cereda was reported in Neurology, May 28, 2013. The report said that the use of pesticides is associated with the development of Parkinson’s disease, which is a neurological disease that causes ...Describe the design of a controlled experiment to determine whether the use of vitamin D supplements reduces the chance of broken bones in women with osteoporosis (weak bones). Assume you have 200 women with osteoporosis to ...The dotplot shows the cholesterol level of 93 adults from the 2010 NHANES data. a. A total cholesterol level of 240mg/dL (milligrams per deciliter) or more is considered unhealthy. Report the number of people in this group ...The table below Exercise 2.30 shows the average lifespan for some mammals in years, according to infoplease.com. Graph these average lifespans and describe the distribution. What is a typical lifespan? Identify the three ...
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