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91Ó°ÊÓ

In estimating the mean score on a fitness exam, we use an original sample of size \(n=30\) and a bootstrap distribution containing 5000 bootstrap samples to obtain a \(95 \%\) confidence interval of 67 to \(73 .\) In Exercises 3.106 to 3.111 , a change in this process is described. If all else stays the same, which of the following confidence intervals \((A, B,\) or \(C)\) is the most likely result after the change: \(\begin{array}{ll}A .66 \text { to } 74 & B .67 \text { to } 73\end{array}\) C. 67.5 to 72.5 Using 10,000 bootstrap samples for the distribution.

Short Answer

Expert verified
The most likely confidence interval after increasing the number of bootstrap samples to 10,000 is Option C: 67.5 to 72.5

Step by step solution

01

Understanding Bootstrap Sampling

In a bootstrap sampling, the sample is repeatedly resampled with replacement to generate a series of simulated samples known as bootstrap samples. These are used to estimate the sampling distribution of a statistic and compute the confidence intervals.
02

Effect of Increasing Bootstrap Samples

Increasing the number of bootstrap samples often results in a narrower confidence interval. This is because the more bootstrap samples we have, the closer our bootstrap distribution will resemble the true sampling distribution, reducing the variability.
03

Choosing the Most Likely Confidence Interval

Looking at the given options of new confidence intervals, Option C: 67.5 to 72.5 is most likely to occur after increasing the bootstrap samples to 10,000. The other intervals A and B are wider while the aim of increasing the samples is to get a narrower interval.

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Key Concepts

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

Confidence Interval
Understanding the concept of a confidence interval is fundamental for any statistics student. A confidence interval gives us a range of values within which we can be confident that the true population parameter (like a mean or a proportion) lies, based on our sample data. For example, a 95% confidence interval of 67 to 73 for a fitness exam score indicates that, if we were to repeat the sampling process numerous times, the true mean would fall within this range 95% of the time.

The confidence level (95%) gives us the probability that the interval contains the true parameter if we were to take many samples. It's crucial to note that the interval itself does not have probabilities – it either contains the true mean or it doesn't. But when we talk about '95% confident', we're talking about this as a long-term frequency if we were to use the same sampling method over and over again.

Improving the understanding of confidence intervals can be aided by remembering a few key points:
  • Margin of Error: A narrower interval suggests a smaller margin of error and, thus, a more precise estimate of the population parameter.
  • Sample Size Impact: A larger sample size generally leads to a narrower confidence interval, assuming the level of confidence is kept constant.
  • Variability: The interval is also affected by the variability in the data; less variability in the sample leads to a narrower interval.
The exercise showcased the effect of increasing the number of bootstrap samples on the width of the confidence interval — an aspect that's important for statistical precision.
Sampling Distribution
The sampling distribution is a concept that students often find perplexing. It is the distribution of a statistic (like the mean or median) that one would get if they could take an infinite number of samples of the same size from a population. In reality, we cannot take an infinite number of samples, but we use mathematical theory and resampling methods like bootstrap sampling to estimate this distribution.

A key property of the sampling distribution is its 'standard error', which measures the variability of a statistic across all possible samples. The standard error decreases with an increase in sample size and is pivotal in constructing confidence intervals. Bootstrap sampling, as employed in the original exercise, is a resampling technique that helps approximate the sampling distribution by taking repeated samples with replacement from the original sample.

Improving comprehension in this area involves grounding in a few essential concepts:
  • Central Limit Theorem: For many datasets, the sampling distribution of the mean will tend to be normally distributed as the sample size increases, which is why normal distribution is often used in statistical tests.
  • Bootstrap Advantage: Bootstrapping can provide a good approximation to the sampling distribution, especially when the shape of the distribution is unknown or the sample size is small.
  • Sample-to-Sample Variability: Students should understand that each sample could potentially produce a different statistic, and the sampling distribution embodies this variability.
In increasing the number of bootstrap samples from 5,000 to 10,000, the aim is to obtain a more accurate estimate of the sampling distribution, thereby leading to a more precise confidence interval.
Statistics Education
Statistics education is crucial in today’s data-driven world. It equips students with the ability to make informed decisions based on data analysis. For ensuring students fully comprehend the material, it is vital to connect theoretical concepts with real-world applications, as was exemplified in the fitness exam scoring exercise.

Effective statistics education should encourage students to engage with the following practices:
  • Active Learning: Students learn best by doing, so exercises involving data collection, analysis, and interpretation are invaluable. Tools like bootstrap sampling provide hands-on experience.
  • Critical Thinking: Students should be encouraged to question the data, understand the limitations of their analyses, and consider the implications of the statistical decisions they make.
  • Applied Knowledge: Linking statistics to real-life scenarios, such as understanding health metrics or analyzing business trends, demonstrates the relevance of statistical tools and theories.
By reinforcing concepts such as confidence intervals and sampling distributions with practical exercises, students are better prepared to use statistical thinking and methods in their academic and professional endeavors. The improvement advice for the exercise can focus on showing visual aids, like confidence interval plots and sampling distribution graphs, and on the importance of a varied number of simulations to illustrate the stability and reliability of the estimated intervals.

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Most popular questions from this chapter

Give information about the proportion of a sample that agrees with a certain statement. Use StatKey or other technology to estimate the standard error from a bootstrap distribution generated from the sample. Then use the standard error to give a \(95 \%\) confidence interval for the proportion of the population to agree with the statement. StatKey tip: Use "CI for Single Proportion" and then "Edit Data" to enter the sample information. In a random sample of 250 people, 180 agree.

SKILL BUILDER 2 In Exercises 3.45 to 3.48 , construct an interval giving a range of plausible values for the given parameter using the given sample statistic and margin of error. For \(p,\) using \(\hat{p}=0.37\) with margin of error 0.02 .

Daily Tip Revenue for a Waitress Data 2.12 on page 123 describes information from a sample of 157 restaurant bills collected at the First Crush bistro. The data is available in RestaurantTips. Two intervals are given below for the average tip left at a restaurant; one is a \(90 \%\) confidence interval and one is a \(99 \%\) confidence interval. Interval A: 3.55 to 4.15 Interval B: 3.35 to 4.35 (a) Which one is the \(90 \%\) confidence interval? Which one is the \(99 \%\) confidence interval? (b) One waitress generally waits on 20 tables in an average shift. Give a range for her expected daily tip revenue, using both \(90 \%\) and \(99 \%\) confidence. Interpret your results.

Is a Car a Necessity? A random sample of \(n=1483\) adults in the US were asked whether they consider a car a necessity or a luxury, \({ }^{31}\) and we find that a \(95 \%\) confidence interval for the proportion saying that it is a necessity is 0.83 to \(0.89 .\) Explain the meaning of this confidence interval in the appropriate context.

Socially Conscious Consumers In March 2015, a Nielsen global online survey "found that consumers are increasingly willing to pay more for socially responsible products."11 Over 30,000 people in 60 countries were polled about their purchasing habits, and \(66 \%\) of respondents said that they were willing to pay more for products and services from companies who are committed to positive social and environmental impact. We are interested in estimating the proportion of all consumers willing to pay more. Give notation for the quantity we are estimating, notation for the quantity we are using to make the estimate, and the value of the best estimate. Be sure to clearly define any parameters in the context of this situation.

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