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According to a Gallup poll conducted January \(5-8,2014,67 \%\) of American adults were dissatisfied with the way income and wealth are distributed in America. Assume that this poll is based on a random sample of 1500 American adults. a. What is the point estimate of the corresponding population proportion?

Short Answer

Expert verified
The point estimate of the corresponding population proportion is 0.67 or 67%.

Step by step solution

01

Identify the sample size and the proportion

In the problem, it is provided that 67% of American adults were dissatisfied, which is the given proportion. This is based on a sample of 1500 American adults. So, the sample size \(n = 1500\) and the sample proportion \(p = 0.67\).
02

Calculate the point estimate

In statistics, we use the formula for the point estimate of the population proportion, which is simply the sample proportion. So, the point estimate in this case would be \(p = 0.67\).

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Key Concepts

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

Population Proportion
The concept of a population proportion refers to a part or fraction of a whole population that exhibits a certain characteristic. In statistics, this could be an interest in knowing what percentage of a large group, like all American adults, have a particular opinion or behavior.
When talking about population proportion, we refer to the entire group, not just a subset. For instance, if we wanted to know how many American adults are dissatisfied with income distribution, the population proportion would represent all American adults who feel this way.
Understanding a population proportion involves collecting data from a representative group, often leading to polls or surveys to infer characteristics, behaviors, or opinions of the entire population.
Sample Proportion
A sample proportion is a statistical measure that reflects the proportion of individuals within a sample exhibiting a particular attribute. It gives us insight into the larger population since testing every single person is often impractical.
In the context of the Gallup poll, the sample proportion is 67%, which indicates that out of the selected sample of 1500 American adults, 67% are dissatisfied with income distribution. The sample proportion is denoted by the symbol \( p \). In mathematical terms, \( p = \frac{x}{n} \), where \( x \) is the number of individuals in the sample with the characteristic, and \( n \) is the total number sampled, which equals \( p = 0.67 \) here. This sample proportion serves as an estimate for the population proportion.
Statistical Poll Analysis
Statistical poll analysis is a method used to understand how survey or poll results can be used to make inferences about a larger population. This involves analyzing the sample data to predict or estimate factors within the entire population.
Key components of statistical poll analysis include:
  • Determining the sample size (which should ideally be large enough to represent the population adequately).
  • Calculating the sample proportion, which aids in estimating the actual population proportion.
  • Consideration of the margin of error, which indicates the uncertainty level around the estimate.
Through effective poll analysis, statisticians can predict trends and behaviors across a larger group, providing valuable insights without surveying everyone.
Gallup Poll
The Gallup poll is a renowned public opinion polling organization that conducts surveys across various demographic and societal issues. Widely respected, Gallup polls are known for their scientific and methodical approach in gathering data to reflect public sentiment.
The Gallup poll mentioned here provides a snapshot of American adults' dissatisfaction with income distribution, with a specific focus on drawing a representative sample of 1500 individuals. This ensures that the findings are not skewed by biases and accurately mirror the larger population's views.
Gallup's methodology emphasizes random sampling to reduce errors and enhance the credibility of their results, making conclusions drawn from their polls trusted references in social and political discussions.

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Most popular questions from this chapter

At Farmer's Dairy, a machine is set to fill 32 -ounce milk cartons. However, this machine does not put exactly 32 ounces of milk into each carton; the amount varies slightly from carton to carton. It is known that when the machine is working properly, the mean net weight of these cartons is 32 ounces. The standard deviation of the amounts of milk in all such cartons is always equal to \(.15\) ounce. The quality control department takes a random sample of 25 such cartons every week, calculates the mean net weight of these cartons, and makes a \(99 \%\) confidence interval for the population mean. If either the upper limit of this confidence interval is greater than \(32.15\) ounces or the lower limit of this confidence interval is less than \(31.85\) ounces, the machine is stopped and adjusted. A recent sample of 25 such cartons produced a mean net weight of \(31.94\) ounces. Based on this sample, will you conclude that the machine needs an adjustment? Assume that the amounts of milk put in all such cartons have an approximate normal distribution.

Briefly explain the difference between a confidence level and a confidence interval.

When calculating a confidence interval for the population mean \(\mu\) with a known population standard deviation \(\sigma\), describe the effects of the following two changes on the confidence interval: (1) doubling the sample size, (2) quadrupling (multiplying by 4) the sample size. Give two reasons why this relationship does not hold true if you are calculating a confidence interval for the population mean \(\mu\) with an unknown population standard deviation.

Briefly explain the similarities and the differences between the standard normal distribution and the \(t\) distribution.

A bank manager wants to know the mean amount owed on credit card accounts that become delinquent. A random sample of 100 delinquent credit card accounts taken by the manager produced a mean amount owed on these accounts equal to \(\$ 2640 .\) The population standard deviation was \(\$ 578\). a. What is the point estimate of the mean amount owed on all delinquent credit card accounts at this bank? b. Construct a \(97 \%\) confidence interval for the mean amount owed on all delinquent credit card accounts for this bank.

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