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The control group (n=78) consisted of children whose blood lead levels were less than 40 ug/100mL in both 19, whereas the exposed group of children (n=46) had blood lead levels of at least 40 ug/100mL in either 1982 or 1983. These readings were used to quantify lead exposure. Each child had his or her blood lead level measured twice, once in 1982 and again in 1983. Rosner (Rosner, Fundamentals of Biostatistics, 1995) presents the data from an observational study which evaluated the effects of lead exposure on neurological and psychological function in children who lived near a lead smelter. The data set " pbkiddat" contains information on a sample of children living near a lead smelter. The prevalence of colic in the general public is estimated to be as low as 7%. For instance, we might be interested in studying the proportion of children living near a lead smelter who have colic. Remember to include all relevant Minitab Express output.Suppose we are interested in estimating the proportion of individuals in a population who have a certain trait. Use Minitab Express and the five-step hypothesis testing procedure given below. We want to know if there is evidence that in the population of all World Campus students, more than 60% are employed full-time. What sample size would be necessary to construct a 95% confidence interval to estimate the proportion of all World Campus students who are employed full-time with a margin of error of 5%? You will need to do hand calculations. Remember to include all relevant Minitab Express output and to clearly identify your answer.Ĭ. If assumptions were met in part A, use the normal approximation method. Use Minitab Express to construct a 95% confidence interval to estimate the proportion of all World Campus students who are employed full-time. Is it appropriate to use the normal approximation method? Show how you checked assumptions.ī. We want use these data to construct a 95% confidence interval to estimate the proportion of all World Campus students who are employed full-time. In that sample of 100, 67 were employed full-time. Data concerning employment status were collected from a sample of 100 World Campus students at the beginning of the Fall 2018 semester. What minimum sample size would be necessary to construct a 95% confidence interval for the mean difference in exam scores with a margin of error of 0.5 points? You will need to do hand calculations. Explain why your test statistic and p value were the same in parts B and C.Į. Remember to include all relevant Minitab Express output.ĭ. Use the five-step hypothesis testing procedure given below. Use Minitab Express to conduct a single sample mean t test given a sample size of 80, sample mean of 5.2076, and sample standard deviation of 5.8854 to determine if there is evidence that the population mean is different from 0. Step 4: Decide between the null and alternative hypothesesĬ. Step 1: Check assumptions and write hypotheses Use Minitab Express to conduct a paired means t test to determine if there is evidence that scores on the two exams are different in the population of all STAT 200 students. Explain why it is appropriate to use the t distribution to approximate the sampling distribution in this scenario.ī. The mean difference, computed as Midterm 1 – Midterm 2, was 5.2076 points with a standard deviation of 5.8854 points. Data were collected from a representative sample of 80 students during the Spring 2018 semester. A STAT 200 instructor wants to know if students tend to score differently on the first and second midterm exams.
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