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Confidence interval to test proportion of US households with a dog

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A humane society claims that less than 35% of U.S. households own a dog. In a random sample of 400 U.S. households, 156 say they own a dog.

(5) Describe the population of interest and calculate the numerical value of the statistic p Ì? that that we will use to estimate the population proportion p.

(5) Construct a 95% confidence interval for the proportion of U.S. households with a dog.

(4) Construct a 99% confidence interval for the proportion of U.S. households with a dog.

(6) Describe the relationship between the confidence level and the size of the confidence interval. Explain why this relationship holds.

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Problem: A humane society claims that less than 35% of U.S. households own a dog. In a random sample of 400 U.S. households, 156 say they own a dog.

a) Describe the population of interest and calculate the numerical value of the statistic p ̂ that that we will use to estimate the population proportion p.

b) Construct a 95% confidence interval for the proportion of U.S. households with a dog.

c) Construct a 99% confidence ...

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The expert examines confidence interval to test proportions of US households with a dog.

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Descriptive statistics for cross-sectional data: term project

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Describe the population and the variable. From the data, plot a histogram, a stem-and-leaf diagram and an ogive (polygon). Also calculate the mean, median, mode, range, standard deviation, and quartiles of the data. Create a boxplot. Explain what this analysis tells you.

In a separate appendix (or spreadsheet), list all 30-50 observations labeled from 1 to 30 (up to 50 if n=50) so I can duplicate your work if necessary.

Since you will be doing a histogram you will need to select a sample that consists of numerical (quantitative) data not categorical (qualitative) data (see p.15). A bar graph is not the same as a histogram so in Excel, click bars (right click properties) /format data series/options/gap width (should equal to zero) and this should get rid of the gaps (histograms do not contain gaps...only bar graphs are used for categorical data. Your textbook describes other methods to provide an acceptable histogram and other graphics. If you have a category/class in the data with zero observations then try to get rid of the gap by extending the width of the class interval or at the very least explain it in your comments. Histograms and other descriptive statistics should not add to the confusion or generate more questions but should answer and explain the data. Look at your descriptive statistics and ask if there are any questions that would be asked and can you answer them by modifying the descriptive statistics or adding a comment or label. See also p. 81, exhibits 2.1 and 2.2.

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