Based On The Class Sample, You Will Create A 95% Confidence ✓ Solved
Based on the class sample, you will create a 95% confidence
Based on the class sample, you will create a 95% confidence interval for the mean age and the proportion of males in the population of all online college students. Note: The goal of the project is to practice making a confidence interval for a mean and proportion with real data. Do not worry about failed assumptions tests and do not make corrections for small sample size. Use primary methods described in text and used on homework.
Using the same excel sheet as last week, answer the following in the “week 5” tab: For the average age, form a 95% confidence interval:
- What distribution should be used?
- What is the critical value?
- What is the error bound?
- What is the lower bound?
- What is the upper bound?
- How do we interpret the results, in context of our study?
For the proportion of males, form a 95% confidence interval:
- What distribution should be used?
- What is the critical value?
- What is the error bound?
- What is the lower bound?
- What is the upper bound?
- How do we interpret the results, in context of our study?
Paper For Above Instructions
The creation of confidence intervals is an essential aspect of statistics that allows researchers to estimate population parameters based on sample data. In this paper, we will calculate a 95% confidence interval for the mean age of online college students as well as the proportion of males in this population. We will employ primary methods as discussed in the course material.
Confidence Interval for Mean Age
Distribution to Use: For estimating the mean age, we will use the t-distribution. This is appropriate when the population standard deviation is unknown, which is often the case with sample data. The t-distribution is particularly useful for smaller sample sizes (typically n
Critical Value: The critical value for a 95% confidence interval, when using the t-distribution, can be determined from the t-table. For this instance, assuming we have a sample size of \( n = 30 \), with \( n - 1 = 29 \) degrees of freedom, the critical t-value (two-tailed) is approximately 2.045.
Error Bound: The error bound, also known as the margin of error (E), is calculated using the formula:
E = t^* (s/√n)
Where \( t^* \) is the critical value, \( s \) is the sample standard deviation, and \( n \) is the sample size. For example, if the sample standard deviation \( s \) is 5 years and the sample size \( n \) is 30, the calculation would be:
E = 2.045 * (5 / √30) ≈ 1.87 years.
Lower Bound: The lower bound of the confidence interval can be calculated using the formula:
Lower Bound = \( \bar{x} - E \)
Assuming the average age \( \bar{x} \) is 25 years, the lower bound would be:
Lower Bound = 25 - 1.87 ≈ 23.13 years.
Upper Bound: The upper bound is calculated similarly:
Upper Bound = \( \bar{x} + E \)
Upper Bound = 25 + 1.87 ≈ 26.87 years.
Interpretation: The interpretation of the 95% confidence interval for the mean age, which ranges from approximately 23.13 years to 26.87 years, means that we are 95% confident that the true mean age of all online college students falls within this interval.
Confidence Interval for Proportion of Males
Distribution to Use: For the proportion of males in this population, we will use the normal approximation to the binomial distribution. This method is applicable when both np and n(1-p) are greater than 5, which ensures that the sampling distribution of the proportion can be adequately approximated by a normal distribution.
Critical Value: The critical value for a 95% confidence interval using the normal distribution is 1.96.
Error Bound: The error bound for the confidence interval for a proportion is calculated using the formula:
E = z^ √(p(1-p)/n)
Where \( z^* \) is the critical value, \( p \) is the sample proportion of males, and \( n \) is the sample size. Assuming a sample size of 100 with 40 males, p would be 0.40. The calculation of the error margin would then be:
E = 1.96 √(0.40 0.60 / 100) ≈ 0.096.
Lower Bound: The lower bound of the confidence interval for the proportion is calculated as:
Lower Bound = p - E = 0.40 - 0.096 ≈ 0.304.
Upper Bound: The upper bound is:
Upper Bound = p + E = 0.40 + 0.096 ≈ 0.496.
Interpretation: This means that we can be 95% confident that the true proportion of males in the population of online college students lies between approximately 30.4% and 49.6%. This is indicative of significant variability in the male representation among online students.
Conclusion
Calculating confidence intervals provides crucial insights into the characteristics of a population based on sample data. The 95% confidence intervals calculated for the mean age and the proportion of males serve as robust estimates, guiding educators and administrators in understanding their student demographics more accurately. The statistics presented highlight the importance of data in informing educational strategies and policies.
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