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91Ó°ÊÓ

One thousand randomly selected adult Americans participated in a survey conducted by the Associated Press (June, 2006). When asked "Do you think it is sometimes justified to lie or do you think lying is never justified?" \(52 \%\) responded that lying was never justified. When asked about lying to avoid hurting someone's feelings, 650 responded that this was often or sometimes OK. a. Construct a \(90 \%\) confidence interval for the proportion of adult Americans who think lying is never justified. b. Construct a \(90 \%\) confidence interval for the proportion of adult American who think that it is often or sometimes OK to lie to avoid hurting someone's feelings. c. Based on the confidence intervals from Parts (a) and (b), comment on the apparent inconsistency in the responses given by the individuals in this sample.

Short Answer

Expert verified
a. The 90% confidence interval for the proportion of adult Americans who thought lying was never justified can be estimated using the formula and is between two values. b. The same process gives the 90% confidence interval for the proportion of adult Americans who thought that lying to not hurt feelings was often or sometimes OK, again between two values. c. The overlap or lack thereof in these intervals will indicate whether the majority of adult Americans have consistent or inconsistent stances on the different types of lying.

Step by step solution

01

- Construct a 90% confidence interval for the proportion of adult Americans who think lying is never justified

Firstly, calculate the sample proportion (\(p̂\)) where \(p̂ = \frac{x}{n}\). Here, \(x\) is the number of successes (people who think lying is never justified) and \(n\) is the total number of observations. For this part of the problem, \(x = 0.52 * 1000 = 520\) and \(n = 1000\), hence \(p̂ = \frac{520}{1000} = 0.52\). Then, calculate the Z-score for a 90% confidence interval (\(Z_{\frac{\alpha}{2}}\) for 90% CI is 1.645). Now using the formula for a confidence interval, we calculate \(CI = 0.52 \pm 1.645 \sqrt{\frac{0.52(1-0.52)}{1000}}\).
02

- Construct a 90% confidence interval for the proportion of adult Americans who think that it is often or sometimes OK to lie to avoid hurting someone's feelings

Again, calculate the sample proportion (\(p̂\)) where \(p̂ = \frac{x}{n}\). For this part of the problem, \(x = 650\) and \(n = 1000\), hence \(p̂ = \frac{650}{1000} = 0.65\). The Z-score for a 90% confidence interval remains the same (\(Z_{\frac{\alpha}{2}} = 1.645\)). Now using the confidence interval formula, we calculate \(CI = 0.65 \pm 1.645 \sqrt{\frac{0.65(1-0.65)}{1000}}\).
03

- Comment on the apparent inconsistency in the responses

Now, compare the two confidence intervals. If they overlap, the results can still be consistent despite seeming contradictory. If they do not overlap, it indicates an inconsistency in the responses. Remember that a confidence interval reflects the range in which we expect the true population parameter to exist given the observed data and the level of confidence.

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Key Concepts

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

Survey Data Analysis
Survey data analysis involves examining and interpreting data collected from a group of participants to make inferences about a larger population. In this exercise, one thousand randomly selected adult Americans were surveyed about their views on lying. The goal of survey data analysis here is to gauge public opinion and quantify it through statistical measures, such as confidence intervals. To begin, researchers need a clear understanding of the survey questions and the interpretation of responses.
  • "Lying is never justified" - 52% of participants chose this option.
  • "Lying to avoid hurting someone's feelings is sometimes/often OK" - Chosen by 650 participants.
Survey data must be carefully recorded to construct accurate statistical models. Each response reflects individual views and variations, which are often captured in aggregate summaries like percentages or proportions. Understanding these responses helps in calculating confidence intervals, which tell us more about the potential opinion of the entire population based on the sample data.
Proportion Calculation
Proportion calculation is crucial in determining the percentage of a population exhibiting a specific trait or opinion. For any survey data, calculating these proportions is the first step towards building confidence intervals. Let's look at how the sample proportions are computed:
  • The first question gives us a proportion of 0.52, as 520 out of 1000 participants believe lying is never justified.
  • For the second question, 650 out of 1000 believe lying is sometimes/often acceptable to spare someone's feelings, giving a proportion of 0.65.
Each of these proportions represents a point estimate of the population parameter. Meaning, they serve as a direct guess or estimation of the proportion of the entire population holding these beliefs. However, sample data is not perfect. So, confidence intervals provide a range of values, increasing the reliability of these estimates by acknowledging potential variation.
Statistical Inconsistency Analysis
Statistical inconsistency analysis examines differences or contradictions within collected data sets. If participants provide answers that seem to conflict logically, such analysis helps in understanding whether these are due to statistical variability or possibly survey errors. For our survey data: - Construct two confidence intervals based on calculated proportions. - First interval: For those who feel lying is never justified. - Second interval: For those who think lying to spare feelings is acceptable. These intervals represent ranges where the true proportions of the population are expected to fall, based on the data. If these intervals overlap, responses might still be consistent statistically, though seemingly contradictory. If they do not overlap, it's indicative of a discrepancy. Such inconsistencies might reflect nuanced views, where respondents differ in context or type of lying considered. Understanding these variances aids in creating accurate and representative interpretations—essential for making informed decisions based on survey data.

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