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A survey question for a sample of 150 individuals yielded 75 Yes responses, 55 No responses, and 20 No Opinions. a. What is the point estimate of the proportion in the population who respond Yes? b. What is the point estimate of the proportion in the population who respond No?

Short Answer

Expert verified
a. 0.5 b. 0.3667

Step by step solution

01

Understand the Point Estimate

A point estimate is a single value that serves as an estimate of a population parameter. In this case, we are asked to find the point estimates for proportions of responses (Yes or No).
02

Calculate the Total Responses

The exercise provides the responses: 75 Yes, 55 No, and 20 No Opinions. Add these to verify the total, which should match the given sample size of 150 individuals. \[ 75 + 55 + 20 = 150 \]
03

Calculate the Point Estimate for Yes Responses

The point estimate for the proportion of Yes responses is calculated by dividing the number of Yes responses by the total number of individuals surveyed. \[ \hat{P}_{Yes} = \frac{75}{150} = 0.5 \]
04

Calculate the Point Estimate for No Responses

Similarly, the point estimate for the proportion of No responses is calculated by dividing the number of No responses by the total number of individuals surveyed. \[ \hat{P}_{No} = \frac{55}{150} \approx 0.3667 \]
05

Verify Complete Information

To ensure we have accounted for all response types, the calculation is verified by ensuring the sum of proportions for Yes, No, and No Opinions equals 1 (or 100%). \[ \hat{P}_{Yes} + \hat{P}_{No} + \hat{P}_{No ext{ }Opinion} = 0.5 + 0.3667 + \frac{20}{150} = 1 \]

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Key Concepts

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

Population Proportion
The population proportion is a vital concept in statistics, often used to represent the fraction of individuals in a larger group that shares a certain characteristic. In this context, the population proportion helps estimate the number of people in a larger demographic who would answer 'Yes' or 'No' in response to a similar survey question as was asked in the sample.

To determine this, a sample from the population is utilized. The sample's characteristics are used to estimate the whole population's characteristics, under the assumption that the sample accurately reflects the population.

The point estimate is a tool to express this representation numerically, often expressed as a decimal or a percentage. For example, if a sample shows that 50% of individuals responded 'Yes,' it suggests that, within the total population, about 50% might share the same response if surveyed.
Sample Survey
A sample survey collects data from a subset of a population to infer results about the overall population. Conducting a sample survey involves selecting a group of individuals that represent the larger group's diverse characteristics as accurately as possible.

In the given exercise, the survey involved 150 individuals, aiming to reflect broader sentiment. To ensure reliable insights, the surveyed sample should be randomly selected and adequately sized, helping minimize biases that could skew the data.

Surveys often strive for simplicity to capture clear responses, as seen with the clear categories of "Yes," "No," and "No Opinion." This clarity aids in subsequent statistical analysis and ensures that the data gathered can be effectively utilized for estimating population proportions.
Statistical Calculation
Statistical calculations are essential in transforming survey data into meaningful insights. Once you have collected data via a survey, the next step is performing calculations to find point estimates or other statistics that summarize the data succinctly.
  • **Verification of Sample Size:** Confirm that the total responses add up to the intended sample size (150 in this case).
  • **Calculation of Proportions:** This involves dividing the number of specific responses by the total number surveyed. For the 'Yes' responses, dividing 75 by 150 yields a proportion of 0.5.
These calculations help put the data into perspective, allowing for the estimation of what might be true of the larger population if the sample is a good representation.
Survey Responses
Survey responses are the raw data collected from individuals during a survey. In this exercise, they include categorizations like 'Yes,' 'No,' and 'No Opinion.' Analyzing these responses is critical in deriving meaningful insights about the population.
  • **Categorical Data:** Survey responses often fall into categories for ease of analysis. Here, each type of response is counted separately.
  • **Importance of Breakdown:** Understanding the breakdown of these categories aids in calculating the point estimates. For example, knowing there were 75 'Yes' responses within a sample of 150 helps compute the proportion quickly.
The primary aim is to convert these responses into actionable data that can influence decision-making or reflect broader trends within the full population. Accurately recording and categorizing these responses is crucial for reliable statistical analysis.

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Most popular questions from this chapter

A researcher reports survey results by stating that the standard error of the mean is \(20 .\) The population standard deviation is 500 a. How large was the sample used in this survey? b. What is the probability that the point estimate was within ±25 of the population mean?

A simple random sample of 5 months of sales data provided the following information: \\[ \begin{array}{lrrrrr} \text {Month:} & 1 & 2 & 3 & 4 & 5 \\ \text {Units Sold:} & 94 & 100 & 85 & 94 & 92 \end{array} \\] a. Develop a point estimate of the population mean number of units sold per month. b. Develop a point estimate of the population standard deviation.

Three firms carry inventories that differ in size. Firm A's inventory contains 2000 items, firm \(\mathrm{B}\) 's inventory contains 5000 items, and firm \(\mathrm{C}\) 's inventory contains 10,000 items. The population standard deviation for the cost of the items in each firm's inventory is \(\sigma=144\) A statistical consultant recommends that each firm take a sample of 50 items from its inventory to provide statistically valid estimates of the average cost per item. Managers of the small firm state that because it has the smallest population, it should be able to make the estimate from a much smaller sample than that required by the larger firms. However, the consultant states that to obtain the same standard error and thus the same precision in the sample results, all firms should use the same sample size regardless of population size. a. Using the finite population correction factor, compute the standard error for each of the three firms given a sample of size 50 . b. What is the probability that for each firm the sample mean \(\bar{x}\) will be within ±25 of the population mean \(\mu ?\)

Suppose a simple random sample of size 50 is selected from a population with \(\sigma=10\) Find the value of the standard error of the mean in each of the following cases (use the finite population correction factor if appropriate). a. The population size is infinite. b. The population size is \(N=50,000\). c. The population size is \(N=5000\). d. The population size is \(N=500\).

BusinessWeek surveyed MBA alumni 10 years after graduation (BusinessWeek, September 22 2003 ). One finding was that alumni spend an average of \(\$ 115.50\) per week eating out socially. You have been asked to conduct a follow-up study by taking a sample of 40 of these MBA alumni. Assume the population standard deviation is \(\$ 35\) a. Show the sampling distribution of \(\bar{x}\), the sample mean weekly expenditure for the \(40 \mathrm{MBA}\) alumni. b. What is the probability the sample mean will be within \(\$ 10\) of the population mean? c. Suppose you find a sample mean of \(\$ 100 .\) What is the probability of finding a sample mean of \(\$ 100\) or less? Would you consider this sample to be an unusually low spending group of alumni? Why or why not?

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