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Spread of Diabetes A random sample of 100 people from different age groups was taken. The mean age of diabetic patients was \(31.32\) years with a margin of error of \(17.4\) years. The distribution of age is normal. (Source: https://www.StatCrunch .com/5.0/viewreport.php?reportid=60000. Accessed via StatCrunch. Owner: pachecodl79.) a. Decide whether each of the following statements is worded correctly for the confidence interval, and fill in the blanks for the correctly worded one(s). i. We are \(95 \%\) confident that the boundaries of the interval are and ii. We are \(95 \%\) confident that the population mean is between and iii. We are \(95 \%\) confident that the sample mean is between \(_{-}\) and b. Can we reject a population mean of 27 years on the basis of these numbers? Explain.

Short Answer

Expert verified
a. Option ii: 'We are 95% confident that the population mean is between ______ and ______' is worded correctly for the confidence interval. The calculated value for the interval is from 13.92 years to 48.72 years. \n b. We cannot reject the population mean of 27 years based on the calculated confidence interval since it falls within the range.

Step by step solution

01

Correct Application of Confidence Interval Phrases

a. The correct wording for a confidence interval is: 'We are 95% confident that the population mean is between ______ and ______.' \nThis is because when we calculate a confidence interval, we estimate a range of values for the population parameter, not the sample statistic. Hence, option ii is correctly worded.
02

Calculate Lower and Upper Limits

Using the mean value and margin of error given, we can calculate the Confidence Interval. The mean age is given as 31.32 years and the margin of error is 17.4 years. So, the lower limit of the confidence interval is calculated as (mean - margin of error) = (31.32 - 17.4) = 13.92 years. And the upper limit is (mean + margin of error) = (31.32 + 17.4) = 48.72 years. Therefore, the confidence interval is from 13.92 years to 48.72 years.
03

Hypothesis Testing

b. To reject a population mean of 27 years, the number has to fall outside the confidence interval. However, 27 years falls within our confidence interval, 13.92 years to 48.72 years. Therefore, we cannot reject a population mean of 27 years based on these numbers.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Mean Age of Diabetic Patients
Understanding the mean age of diabetic patients within a study is crucial for medical research and public health planning. The mean age gives us a central point around which the ages of all diabetic patients in the survey are distributed.

Exercise Improvement Advice: To improve clarity, it's important to note that the mean age is an average, which can be significantly influenced by extreme ages in the sample. Therefore, when considering the mean age of 31.32 years, we must be cautious and consider the possibility of outliers skewing this average. Additionally, it might be helpful to compare this mean age with other studies or known benchmarks to understand how this specific sample relates to the broader population.
Margin of Error
The margin of error is a statistic expressing the amount of random sampling error in a survey's results. It represents how much the estimated mean age can fluctuate due to the randomness of the sample chosen. A margin of error of 17.4 years is quite high, which indicates that the true mean age of all diabetic patients could be quite different from the 31.32 years observed in our sample.

Exercise Improvement Advice: To accurately interpret the margin of error, one should highlight its relationship with sample size and variance within the data. A larger sample size can reduce the margin of error, leading to more precise estimates. Additionally, including confidence levels (e.g., 95%) when reporting the margin of error helps to specify the degree of certainty about the interval containing the population mean.
Normal Distribution
A normal distribution is a bell-shaped distribution that is symmetric about the mean, indicating that data near the mean are more frequent in occurrence than data far from the mean. In the context of the age of diabetic patients, if the distribution is indeed normal, we can apply various statistical methods, such as hypothesis testing and confidence intervals, with more assurance of their validity.

Exercise Improvement Advice: When teaching about normal distribution, it's beneficial to illustrate with graphs and explain properties such as the empirical rule, which states approximately 68%, 95%, and 99.7% of the data within one, two, and three standard deviations from the mean, respectively. This helps students visualize and better understand the data's distribution.
Hypothesis Testing
Hypothesis testing is a method used to decide whether there is enough evidence in a sample of data to infer that a certain condition is true for the entire population. In the exercise provided, hypothesis testing is used to determine if we can reject the null hypothesis that the population mean age of diabetic patients is 27 years.

To reach a conclusion, we compare the proposed mean to the calculated confidence interval. Since the age of 27 is within the interval of 13.92 to 48.72 years, we do not have sufficient evidence to reject the hypothesis. This result implies that, statistically, the mean age of the population could be 27 years.

Exercise Improvement Advice: It's important to explain the concept of 'statistical significance' in the context of hypothesis testing. Furthermore, it would be beneficial to delve into Type I and Type II errors, which can occur during hypothesis testing, and how they relate to the confidence level chosen for the study.

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Most popular questions from this chapter

A McDonald's fact sheet says their cones should weigh \(3.18\) ounces (converted from grams). Suppose you take a random sample of four cones, and the weights are \(4.2,3.4,3.9\), and \(4.4\) ounces. Assume that the population distribution is Normal, and, for all three parts, report the alternative hypothesis, the \(t\) -value, the p-value, and your conclusion. The null hypothesis in all three cases is that the population mean is \(3.18\) ounces. a. Test the hypothesis that the cones do not have a population mean of \(3.18\) ounces. b. Test the hypothesis that the cones have a population mean less than \(3.18\) ounces. c. Test the hypothesis that the cones have a population mean greater than 3.18 ounces.

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Choose a \(t\) -test for each situation: one-sample \(t\) -test, twosample \(t\) -test, paired \(t\) -test, and no \(t\) -test. a. A random sample of students of a college is asked their statistics score. Our goal is to determine whether the mean score for students of that college is significantly different from the population mean score for all the students at the university. b. A researcher goes to a department store and observes whether each person coming in is male or female and whether they finish their shopping within 15 minutes (yes or no). c. A researcher visits a hospital at night and records the number of cases handled by the doctors on duty and the gender of the doctors.

Babies Weights (Example 2) Some sources report that the weights of full-term newborn babies have a mean of 7 pounds and a standard deviation of \(0.6\) pound and are Normally distributed. a. What is the probability that one newborn baby will have a weight within \(0.6\) pound of the mean-that is, between \(6.4\) and \(7.6\) pounds, or within one standard deviation of the mean? b. What is the probability the average of four babies' weights will be within \(0.6\) pound of the mean; will be between \(6.4\) and \(7.6\) pounds? c. Explain the difference between a and \(\mathrm{b}\).

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