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Graduation In October 2000 the U.S. Department of Commerce reported the results of a large-scale survey on high school graduation. Researchers contacted more than 25,000 randomly chosen Americans aged 24 years to see if they had finished high school; \(84.9 \%\) of the 12,460 males and \(88.1 \%\) of the 12,678 females indicated that they had high school diplomas. a) Are the assumptions and conditions necessary for inference satisfied? Explain. b) Create a \(95 \%\) confidence interval for the difference in graduation rates between males and females. c) Interpret your confidence interval. d) Does this provide strong evidence that girls are more likely than boys to complete high school? Explain.

Short Answer

Expert verified
Yes, conditions are met. The 95% CI is [-0.04376, -0.02024]. Girls are more likely to graduate.

Step by step solution

01

Checking Assumptions and Conditions

To perform inference, we need to check the conditions for applying a confidence interval for a difference in proportions. These include: - **Randomization:** The data must come from a well-conducted random sample. The problem states a random sample was used, so this condition is satisfied. - **10% Condition:** Each sample (males and females) should not exceed 10% of the entire population aged 24. Assuming there are more than 124,600 males and females respectively in this age bracket in the U.S., this condition is met. - **Success/Failure Condition:** Both groups must have at least 10 expected successes and failures. For males, there are 10,576 successes (graduated) and 1,884 failures. For females, there are 11,169 successes and 1,509 failures. All numbers exceed 10, satisfying this condition.
02

Setting Up the Confidence Interval Formula

The formula for the confidence interval for the difference between two proportions is:\[(p_1 - p_2) \pm Z^* \cdot \sqrt{ \frac{p_1(1-p_1)}{n_1} + \frac{p_2(1-p_2)}{n_2} }\]where:- \(p_1 = 0.849\), \(n_1 = 12,460\) for males,- \(p_2 = 0.881\), \(n_2 = 12,678\) for females,- \(Z^*\) is the Z-score for a 95% confidence interval, approximately 1.96.
03

Calculating the Standard Error

Calculate the standard error (SE) for the difference in proportions:\[SE = \sqrt{ \frac{0.849 \times (1-0.849)}{12,460} + \frac{0.881 \times (1-0.881)}{12,678} }\]Plugging in the values, we get:\[SE = \sqrt{ \frac{0.849 \times 0.151}{12,460} + \frac{0.881 \times 0.119}{12,678} } \approx 0.006\]
04

Calculating the Confidence Interval

Use the standard error to calculate the confidence interval:\[(0.849 - 0.881) \pm 1.96 \times 0.006\]This simplifies to:\[-0.032 \pm 0.01176\]The interval is:\[-0.04376, -0.02024\]
05

Interpreting the Confidence Interval

The 95% confidence interval for the difference in high school graduation rates between males and females is \([-0.04376, -0.02024]\). This means we can be 95% confident that the true difference in graduation rates (female - male) is between -4.376% and -2.024%. Since the entire interval is negative, it indicates that a smaller proportion of males graduate compared to females.
06

Evaluating the Evidence

Since the confidence interval does not contain zero and is entirely negative, there is strong evidence to suggest that females are more likely to graduate high school than males. The fact that none of the possible values for the difference includes zero supports the conclusion of a statistically significant difference.

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Key Concepts

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

Difference in Proportions
Understanding the difference in proportions is crucial when comparing two groups. In this case, it involves examining the high school graduation rates of males and females. The difference in proportions is calculated by subtracting one group's proportion from another. Here, this equates to the proportion of females graduating high school minus the proportion of males graduating. This difference helps to determine if there is a statistically significant variation between the two groups. When statistical evidence suggests a non-zero difference, it implies that one group consistently achieves a higher or lower outcome than the other. Such analysis is key in fields like education, where identifying disparities can lead to policy changes or targeted interventions.
High School Graduation Rates
High school graduation rates are an important metric in assessing educational outcomes. In the U.S., these rates can help identify broader social issues, such as gender disparities in education. The graduation rate is the proportion of students who successfully complete high school and is often used to gauge the effectiveness of the education system. For the current example, we looked at males and females aged 24. The observed graduation rates were 84.9% for males and 88.1% for females. These percentages are derived from survey data and demonstrate a baseline for evaluating differences between gender groups, which could be influenced by various factors including socio-economic status, educational policies, and cultural norms.
Statistical Inference
Statistical inference allows us to draw conclusions about a population based on sample data. This involves using techniques like confidence intervals to estimate the population parameters. In our example, we were interested in the difference between the graduation rates of males and females. By employing statistical inference, we could establish a range—the confidence interval—for the true difference in proportions based on our sample. This range helps us understand where the actual population parameter likely falls. For the given data, our confidence interval was [-0.04376, -0.02024], indicating a likely difference affirming that females tend to graduate more than males. By analyzing whether this interval includes zero, we can judge the significance of the difference, adding depth to our understanding.
Survey Data Analysis
Survey data analysis is essential to extracting usable insights from collected data, especially with large samples like the one from the 2000 U.S. Department of Commerce research. This process involves scrutinizing the responses from over 25,000 randomly selected individuals to ensure the data quality. Besides checking the randomness of the sample, analysts also confirm that the sample is representative of the larger population, satisfying various assumptions in the process. By focusing on high school graduation rates, survey data helps infer broader social trends. It requires careful consideration of potential biases, and responses are systematically analyzed to derive meaningful statistical conclusions like the ones we've discussed, ensuring rigorous and reliable outcomes.

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Most popular questions from this chapter

Arthritis The Centers for Disease Control and Prevention reported a survey of randomly selected Americans age 65 and older, which found that 411 of 1012 men and 535 of 1062 women suffered from some form of arthritis. a) Are the assumptions and conditions necessary for inference satisfied? Explain. b) Create a \(95 \%\) confidence interval for the difference in the proportions of senior men and women who have this disease. c) Interpret your interval in this context. d) Does this confidence interval suggest that arthritis is more likely to afflict women than men? Explain.

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