Week 8

Assignments Module Eight Chapter Eight

Part One: On the discussion board, please respond to the following:

Please choose one of the following articles or videos.

Articles

Stats 101: What you need to know about statisticsLinks to an external site.

How to talk statistics to Military OfficersLinks to an external site.

A few things leaders need to know about data and analysis – Part OneLinks to an external site.

A few things leaders need to know about data and analysis – Part TwoLinks to an external site.

Statistics at WarLinks to an external site.

5 Major importance & Role of statistics in businessLinks to an external site.

 

Videos

Quantitative Data Analysis 101 TutorialLinks to an external site.(~28 minutes)

What is statistics: Crash Course StatisticsLinks to an external site.(~13 minutes)

War: Crash Course StatisticsLinks to an external site.(~11 minutes)

A Beginners Guide to the Data Analysis ProcessLinks to an external site.(~10 minutes)

Teach me Statistics in half an hourLinks to an external site.(~35 minutes)

 

Or would you like to find your own?  If so, before you do the work, please let me know what you would like to review. Please email me a link to the video or article. Keep in mind a video needs to be at least 10 minutes in length, an article must be meaningful with content that can support the discussion centering on the questions listed below.

(Watch or read your choice or an article or video.)

Please answer the following questions: Briefly summarize the contents, two or three sentences. What was surprising or new or interesting to you? How could this information apply to your current work? Please write one question you have about the topic or reading. If you cannot or do not have a question, create a question that can be supported from the reading or by watching the video.

Please clearly label the title of your topic when posting.

Please reply to one classmate by answering the question that was posted. In some situations, you might need to review a second article or video.

Please post in the discussion board labeled, “What have you learned this semester.”

 

Due date Initial Post: Saturday November 12, 2022; 11:59PM EST

Reply to Another Post: Wednesday November 15, 2022: 11:59PM EST

 

Part Two

Chapter Seven Analysis, this work needs to be submitted.

Using the posted solution set, when it is available, compare your submitted work for each assigned question to the answers.

List for each question:

• Whether or not you got the solution correct or incorrect.
• If you got a question incorrect, please discuss why is was incorrect.  Please include what were the differences between your work and the given solutions.
• If you got a question correct.  Please list the number and the word correct.
• Each question for the assignment should be “analyzed” and each number assigned should be represented in the analysis assignment.

An example of what is expected for this assignment can be found in the “Additional Information” module.

You do not need to wait for the grade book to be officially updated before completing this assignment.  You can complete this work as soon as the solution set is made available.  If you do not submit an assignment by the date it is due, or before the solutions are posted, then you cannot complete the analysis assignment.  No exceptions are made for the analysis assignment.

Please submit online as an attachment.

Due date: Wednesday November 16, 2022: 11:59PM EST

 

Part Three

This assignment does NOT need to be submitted.  The list below represents suggested question to use for practice. You do not need to submit your solutions. You do need to practice. At the end of the week, I will post solution sets to the problems.  Please practice and review your responses to the answers. Be sure to analyze your work by comparing it to the posted solutions.

 

The problems I would assign: Text book Chapter Problems:

Chapter Eight Work: p. 250: 8.5; 8.7; p. 257: 8.19; 8.20; p. 260: 8.28; p. 265: 8.43; pp. 265 – 266: 8.48

 

Non-textbook Problems:

Multiple Choice:

1. Which of the following statements are correct concerning a 95% confident interval?
2. a) There is a 0.05 probability the population parameter of interest is not contained within the interval.
3. b) There is a 0.95 probability that the population parameter of interest is contained within the interval.
4. c) In computing confidence intervals from 20 samples, 19 of the intervals would contain the population mean.
5. d) If you were to produce all possible confidence intervals using the sample mean of each sample of a given size from the population, then 95% of the intervals would contain the population mean.

 

2. A confidence interval was used to estimate the proportion of government employees who are part of HR. A random sample of 72 employees generated the following 90% confidence interval: (0.438, 0.642). What total size sample would be necessary if we wanted to estimate the true proportion to within 0.08 using 95% confidence?
3. a) 105
4. b) 150
5. c) 420
6. d) 597

 

3. The Agency Supervisor wants to know the GG levels of incomes with the protection division. The population standard deviation is known to be $1000. A random sample of 50 individuals resulted in a mean income of $15,000.  What is the width of the 90% confidence interval?
4. a) $232.60
5. b) $364.30
6. c) $465.23
7. d) $728.60

 

4. In the construction of confidence intervals, if all other quantities are unchanged, an increase in the sample size will lead to what change in the interval?
5. a) narrower
6. b) wider
7. c) less significant
8. d) biased

 

8.5  A market researcher selects a simple random sample of

n=100

Twitter users from a population of more than 100 million Twitter-registered users. After analyzing the sample, she states that she has 95% confidence that the mean time spent on Twitter per day is between 15 and 57 minutes. Explain the meaning of this statement.

 

8.7 Consider the confidence interval estimate discussed in Problem 8.5. Suppose the population mean time spent on Twitter is 46 minutes a day. Is the confidence interval estimate stated in Problem 8.5 correct? Explain.

 

8.19 How much time do commuters living in or near cities spend commuting to work each week? The file [Commuting Time] contains the average weekly commuting time in 30 U.S. cities.

Source: Data extracted from Office of the New York City Comptroller, “NYC Economics Brief,” March 2015, p. 3.

1. Construct a 95% confidence interval estimate for the population mean commuting time.
2. Interpret the interval constructed in (a).
3. What assumption must you make about the population distribution in order to construct the confidence interval estimate in (a)?
4. Do you think that the assumption needed in order to construct the confidence interval estimate in (a) is valid? Explain.

 

8.20 The Super Bowl, watched by close to 200 million Americans, is also a big event for advertisers. The file [Super Bowl Ad Ratings] contains the rating of ads that ran between the opening kickoff and the final whistle.

Source: Data extracted from www.admeter.usatoday.com/results/2019

For ads that ran before halftime and ads that ran at halftime or after separately:

1. Construct a 95% confidence interval estimate for the population mean ad rating.
2. Interpret the interval constructed in (a).
3. What conclusions can you reach about the ad ratings of ads that ran before halftime and ads that ran at halftime or after?
4. What assumption must you make about the population distribution in order to construct the confidence interval estimate in (a)?
5. Do you think that the assumption needed in order to construct the confidence interval estimate in (a) is valid? Explain.

 

 

SELF TEST 8.28 A cellphone provider has the business objective of wanting to estimate the proportion of subscribers who would upgrade to a new cellphone with improved features if it were made available at a substantially reduced cost. Data are collected from a random sample of 500 subscribers. The results indicate that 135 of the subscribers would upgrade to a new cellphone at a reduced cost.

1. Construct a 99% confidence interval estimate for the population proportion of subscribers that would upgrade to a new cellphone at a reduced cost.
2. How would the manager in charge of promotional programs use the results in (a)?

 

 

8.43 An advertising media analyst wants to estimate the mean amount of time that consumers spend with digital media daily. From past studies, the standard deviation is estimated as 45 minutes.

1. What sample size is needed if the media analyst wants to be 90% confident of being correct to within

±5

minutes?

1. If 99% confidence is desired, how many consumers need to be selected?

 

8.48 Cybersecurity is a critical business issue that demands the attention of business and IT executives. According to a study released by PwC, 38% of surveyed business and IT executives reported phishing scams at their institutions.

Source: Data extracted from “Toward new possibilities in threat management,” PwC, 2017 pwc.to/2kwhPJv.

1. If you conduct a follow-up study to estimate the population proportion of business and IT executives reporting phishing scams at their institutions, would you use a

π

of 0.38 or 0.50 in the sample size formula?

1. Using your answer in part (a), find the sample size necessary to estimate, with 95% confidence, the population proportion to within

±0.03.