As we have examined throughout the course, data is collected, summarized, and presented to the public for a variety of reasons. The graphics below presents the results for two surveys: one for why small business owners want better customer service skills and the other for the reasons cell phone uses like texting. This case study will review the elements of inferential statistics (sampling distributions, confidence intervals, hypothesis testing) and apply them to a real-world situation. (Source: GfK Roper for Best Buy Mobile) Top Five Reasons Percentage of Responses Customer service 63% Marketing/sales 58% Financial management 48% Decision making 40% Negotiation 30% Reasons We Like Texting Percentage of Responses Convenience for basic information 79% Works where talking won't do 75% Quicker than calling 56% Easier when facing arguments 37% Dislike phone conversations 27% Great for flirting 25% Questions 1 - 3 Refer to the Survey Results on Customer Service 1. Refer to the fine print in the graphic to answer the following questions about the survey. a) How many surveys were submitted? b) How would readers know multiple responses were permitted if it had not been stated? c) Based on the information in the graphic, provide a general interval estimate for the population parameter for ONE of the identified. Define the parameter and explain the process you used to determine the interval estimate. 2. Select ONE of the reasons for wanting better customer service skills that you did NOT use to answer #1. a) For the selected reason, define the population parameter, p, and identify n and from the graphic and fine print. Determine if the distribution of sample proportions is approximately normal, or not. Justify your response. b) Use the values to determine the mean and standard error of a sampling distribution of sample proportions for samples of size n. Show the work which supports your answer.

3. Select ONE of the reasons for wanting better customer service skills that you did NOT use to answer #1 or #2. a) Define the population parameter, p, for the selected reason and identify a point estimate for the true population proportion. b) Determine the margin of error for a confidence interval (You choose the confidence level). c) Identify and interpret the corresponding confidence interval for the population parameter. Questions 4-6 Refer to the Survey Results on Texting 4. Select ONE of the reasons in the survey results on texting. This reason will be used for questions 4-6. For the selected reason: a) Define the population parameter p for the selected reason and make a claim about the defined population parameter. b) Determine the minimum sample size needed for a distribution of sample proportions, , to be normally distributed. Explain your reasoning and include the necessary computations. c) Choose a sample size, n, based on the results of part b) so that the distribution of sample proportions will be normally distributed. Identify mean and standard error of a sampling distribution of proportions based on the survey results and the selected sample of size n. 5. Using the SAME reason you selected for #4, create a one question survey to administer to cell phone users. The survey must be administered to at least n cell phone users, based on the value of n determined in #4. The question should be posed in the form "Do you like texting because (fill in the blank)? Yes or No." a) Describe how you administered the survey. Refer to Chapter 1 to identify the type of sampling you used and any biases that may exist in the sampling. b) State the question you presented and the summary statistics. Attach a file with the individual responses (yes or no) for each respondent. 6. Continuing with the SAME reason used in #4-5, assume the value in the graphic/table is the population to be tested (null hypothesis). a) State the hypotheses (null and alternate) based on the claim you made in #4a. b) Select a significance level for the test and write the corresponding decision rule. c) Use the sampling distribution in #4 to execute the test based on the sample data in #5. d) State the decision based on the rule in #6b and the results in #6c. e) Interpret the decision in terms of the claim in #4a.