Faculty of Business, Economics and Law

Bachelor of Business

Statistics for Business

ECON862

Trimester 1 2020

ASSIGNMENT 3

Answer all questions.

There are 40 marks in total.

Section 1 – Statistical Inference and Confidence Intervals

Question 1 (10 Marks)

The owner of a sporting goods store surveys a group of customers on (i) the average amount spent, and (ii) whether they purchased at least one item of clothing.

The results of a sample of 80 customers are:

Average amount spent: X ¯=49.50

Standard deviation: S=9.50.

Number who bought an item of supporter’s apparel: 20.

Construct a 95% confidence interval for the mean amount spent per shopper.

Construct a 95% confidence interval for the proportion of shoppers who bought at least one item of supporter’s apparel.

The owner of a competing store decides to conduct his own survey.

What sample size does he need if he wants to estimate a 90% confidence interval for the mean amount spent to within ±$3.00, assuming a standard deviation of $8.50?

What sample size does he need to estimate a 90% confidence interval for the proportion who purchase at least one item of supporter’s apparel to within ±0.05?

Based on your answers to c) and d), how large a sample should the store owner use?

Section 2 – Hypothesis Testing: One-Sample Tests

Question 2 (5 Marks)

You work for a company that tests new pharmaceutical products. You are currently testing a new product. From a sample of 300 subjects, 184 report an improvement in their symptoms from taking the new product. The existing product improves the symptoms for 60% of people who take it.

State the null and alternative hypotheses that you would use to test the effectiveness of the new product.

Explain the risks associated with Type 1 and Type 2 errors in this context.

Which of the errors is more serious in this context? Give reasons for your answer.

Question 3 (5 Marks)

Back at the sports store from question 1, the owner decides to use significance tests to better understand the behaviour of his customers. Starting with a new sample of 60 customers, he finds:

Average amount spent: X ¯= 42.8

Standard deviation: S = 11.7

14 customers purchased an item of supporter’s apparel.

At the 5% significance level, is there evidence that the mean spend is different from $40.00? State the null and alternative hypothesis.

Find the p-value in a).

At the 5% level, is there evidence that fewer than 10% of customers purchase at least one item of supporter’s apparel.

Section 3 – Two Sample Tests

Question 4 (10 Marks)

A researcher claims that New Zealanders spend more time exercising than Australians. The researcher takes a random sample of 41 New Zealanders and finds that they spend an average of 130 minutes per day exercising, with a standard deviation of 24. A sample of 61 Australians averaged 110 minutes a day of exercise, with a standard deviation of 16.

Assuming equal variances, test the claim that New Zealanders exercise more than Australians at the 0.05 significance level.

Assuming unequal variances, repeat the test at the 0.05 significance level.

Test whether the variances are equal at the 0.05 significance level.

Based on your answer to part c), which was the appropriate test for the means (a), or b))? Give reasons for your answer.

Explain the unequal variances problem and its relevance, if any, to your conclusions about whether New Zealanders exercise more than Australians.

Section 4 – Analysis of Variance

Question 5 (6 Marks)

Test, at the 5% significance level, to discover whether differences exist between the population means given the statistics below. Remember to state the null and alternative hypotheses clearly.

Group 1 Group 2 Group 3

12 18 19

7 17 15

14 7 18

15 10 16

Question 6 (4 Marks)

A researcher studying four different populations proposes the following:

H_0 : µ_1=µ_2=µ_3=µ_4

H_1 : not all µ_i are equal (i=1,2,3,4)

He takes samples from each of the populations, obtaining the following data:

Group 1 Group 2 Group 3 Group 4

Sample mean 110 105 91 102

Sample size 8 9 5 6

The within-group variation of the data (SSW) is equal to 108.

Using the Tukey-Kramer procedure, calculate the critical range for making a comparison of groups 1 and 4.

Using the data and your answer to part (a), explain whether or not the null hypothesis should be rejected.

~end~

Bachelor of Business

Statistics for Business

ECON862

Trimester 1 2020

ASSIGNMENT 3

Answer all questions.

There are 40 marks in total.

Section 1 – Statistical Inference and Confidence Intervals

Question 1 (10 Marks)

The owner of a sporting goods store surveys a group of customers on (i) the average amount spent, and (ii) whether they purchased at least one item of clothing.

The results of a sample of 80 customers are:

Average amount spent: X ¯=49.50

Standard deviation: S=9.50.

Number who bought an item of supporter’s apparel: 20.

Construct a 95% confidence interval for the mean amount spent per shopper.

Construct a 95% confidence interval for the proportion of shoppers who bought at least one item of supporter’s apparel.

The owner of a competing store decides to conduct his own survey.

What sample size does he need if he wants to estimate a 90% confidence interval for the mean amount spent to within ±$3.00, assuming a standard deviation of $8.50?

What sample size does he need to estimate a 90% confidence interval for the proportion who purchase at least one item of supporter’s apparel to within ±0.05?

Based on your answers to c) and d), how large a sample should the store owner use?

Section 2 – Hypothesis Testing: One-Sample Tests

Question 2 (5 Marks)

You work for a company that tests new pharmaceutical products. You are currently testing a new product. From a sample of 300 subjects, 184 report an improvement in their symptoms from taking the new product. The existing product improves the symptoms for 60% of people who take it.

State the null and alternative hypotheses that you would use to test the effectiveness of the new product.

Explain the risks associated with Type 1 and Type 2 errors in this context.

Which of the errors is more serious in this context? Give reasons for your answer.

Question 3 (5 Marks)

Back at the sports store from question 1, the owner decides to use significance tests to better understand the behaviour of his customers. Starting with a new sample of 60 customers, he finds:

Average amount spent: X ¯= 42.8

Standard deviation: S = 11.7

14 customers purchased an item of supporter’s apparel.

At the 5% significance level, is there evidence that the mean spend is different from $40.00? State the null and alternative hypothesis.

Find the p-value in a).

At the 5% level, is there evidence that fewer than 10% of customers purchase at least one item of supporter’s apparel.

Section 3 – Two Sample Tests

Question 4 (10 Marks)

A researcher claims that New Zealanders spend more time exercising than Australians. The researcher takes a random sample of 41 New Zealanders and finds that they spend an average of 130 minutes per day exercising, with a standard deviation of 24. A sample of 61 Australians averaged 110 minutes a day of exercise, with a standard deviation of 16.

Assuming equal variances, test the claim that New Zealanders exercise more than Australians at the 0.05 significance level.

Assuming unequal variances, repeat the test at the 0.05 significance level.

Test whether the variances are equal at the 0.05 significance level.

Based on your answer to part c), which was the appropriate test for the means (a), or b))? Give reasons for your answer.

Explain the unequal variances problem and its relevance, if any, to your conclusions about whether New Zealanders exercise more than Australians.

Section 4 – Analysis of Variance

Question 5 (6 Marks)

Test, at the 5% significance level, to discover whether differences exist between the population means given the statistics below. Remember to state the null and alternative hypotheses clearly.

Group 1 Group 2 Group 3

12 18 19

7 17 15

14 7 18

15 10 16

Question 6 (4 Marks)

A researcher studying four different populations proposes the following:

H_0 : µ_1=µ_2=µ_3=µ_4

H_1 : not all µ_i are equal (i=1,2,3,4)

He takes samples from each of the populations, obtaining the following data:

Group 1 Group 2 Group 3 Group 4

Sample mean 110 105 91 102

Sample size 8 9 5 6

The within-group variation of the data (SSW) is equal to 108.

Using the Tukey-Kramer procedure, calculate the critical range for making a comparison of groups 1 and 4.

Using the data and your answer to part (a), explain whether or not the null hypothesis should be rejected.

~end~

Editable Microsoft Word Document

Word Count: 1138 words including Calculation work

This above price is for already used answers. Please do not submit them directly as it may lead to plagiarism. Once paid, the deal will be non-refundable and there is no after-sale support for the quality or modification of the contents. Either use them for learning purpose or re-write them in your own language. If you are looking for new unused assignment, please use live chat to discuss and get best possible quote.

In assessment two students are required to write a 2,000 word essay and a 50-100 word reflection relating to the given case study (see detailed instructions below) and submit it via the assessment two...[Assignment 2] Explain Cost of quality project planning in a company. Prepare a project plan for implementing cost of quality for the company you choose which has at least one ISO. The plan should give...HOLMES INSTITUTEFACULTY OFHIGHER EDUCATIONAssessment Details and Submission GuidelinesTrimester T1 2021Unit Code HS1031Unit Title Introduction to ProgrammingAssessment Type IndividualAssessment Title Individual...CRIT3000 S1_2021 Complex Nursing Practice 1: Skills Assessment (Report) Marking Rubric What do we need to do?Unit Learning Outcome assessed:Use clinical knowledge and skills to conduct a comprehensive...Due DateTo Turnitin by Week 8, 10:00 pm Sydney, Australia Time, Thursday, 22 April 2021.Length1200 words. The 1200-word limit includes all text added to the template, including main text, title, heading,...Assessment 2: Case StudyDue date: Session 12Group/individual: IndividualWord count / Time provided: 2500 WordsWeighting: 30%Unit Learning Outcomes: ULO3, ULO4, ULO5Assessment Details:The case study will...Assessment Type ReportAssessment Number 2AssessmentWeighting Case Study40%Due Date/Time Week 1129th May 2020 via Moodle Turnitin 5:00pm (AEST)Assessment DescriptionYou are to provide a security architectural...**Show All Questions**