Purchase Solution

Finding the confidence interval for poll or survey results

Not what you're looking for?

Ask Custom Question

Quality Progress, Feburary 2005, reports on the results achieved by Bank of America in improving customer satisfaction and customer loyalty by listening to the "voice of the customer". A key measure of customer satisfaction is the response on a scale from 1 to 10 to the question: "Considering all the business you do with Bank of America, what is your overall satisfaction with Bank of America?"

Suppose that a random sample of 350 current customers results in 195 customers with a response of 9 or 10 representing "customer delight". Find a 95 percent confidence interval for the true proportion of all current Bank of America customers who would respond with a 9 or 10. Are we 95 percent confident that this proportion exceeds .48, the historical proportion of customer delight for Bank of America?

Purchase this Solution
Solution Preview

When a poll or survey is conducted, and we can assume we have a simple random sample from a large population, we can calculate confidence intervals using the standard error. The formula for standard error is Sqrt[p(1-p)/n], where p is the percent of people giving a certain answer (in this case rating service 9 or 10) ...

Purchase this Solution
Free BrainMass Quizzes
Measures of Central Tendency

This quiz evaluates the students understanding of the measures of central tendency seen in statistics. This quiz is specifically designed to incorporate the measures of central tendency as they relate to psychological research.

Know Your Statistical Concepts

Each question is a choice-summary multiple choice question that presents you with a statistical concept and then 4 numbered statements. You must decide which (if any) of the numbered statements is/are true as they relate to the statistical concept.

Measures of Central Tendency

Tests knowledge of the three main measures of central tendency, including some simple calculation questions.

Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

View More Free Quizzes
Related BrainMass Solutions

  • Speculations about a study result

    If this poll had been based instead on 5000 adults, do you think the "95% confidence interval" would be wider or narrower than the interval given?

  • Testing of hypothesis

    Do the confidence interval limits contain 0, and what is the significance of whether they do or do not?

  • Testing of proportion

    Are these Gallup poll results consistent with those obtained by the survey conducted by the Marist Institute for The Public Opinion? Explain.

  • Confidence Interval for Proportion

    343409 Confidence Interval for Proportion On January 7, 2000, the Gallup Organization released the results of a poll comparing the lifestyles of today with previous times.

  • Confidence interval for population proportion

    120681 Confidence interval for population proportion 1. Consider the following results for independent samples taken from two populations.

  • Statistical Processes

    Determine a 95% confidence interval for each of the above results.

  • Finding the confidence interval for a proportion in an election

    a) The 95% confidence interval for the first poll is ___

    The 95% confidence interval for the second poll is ___

    The 95% confidence interval for the third poll is ___

  • Sample size and confidence interval for proportion

    would or would not be okay for a newspaper to make this statement: "Based on results from recent survey,the majority of Minnesotans are opposed to the photo-cop legislation. 3.A common criticism of surveys is that they poll only a very small percentage

  • Confidence interval for proportion

    230816 Confidence interval for a proportion: Example problem Death Penalty Survey: In a Gallup poll, 491 randomly selected adults were asked whether they are in favor of the death penalty for a person convicted or murder, and 65% of them said that they

View More Related Solutions