MNGT213 Assessment 3 2022/23
Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit
MNGT213 Assessment 32022/23
ASSESSMENT-SPECIFIC ADVICE
Assessment 3 is on sampling distributions, confidence intervals, hypothesis testing, and linear regression.
Attempt all the questions. You are required to show your working out to obtain full marks or solutions where appropriate, i.e. you need to show that you are using the correct formula. Method marks will be available if you show that you have followed the correct process but have made an error in your calculations. Reduced or zero marks will be given if it is not clear how you arrived at your solution, i.e., you have not shown your working out. Round your answers to 2 - 4 d.p. unless stated otherwise in the question.
You can use Excel to work on this assessment. When using Excel, provide the outputs of your data analysis.
DEADLINE
The deadline for your submission is Friday, 20 January, 12 noon. Please note, technical issues are rarely accepted for excusing late submission, therefore it is strongly recommended you do not leave your submission to the last minute.
SUBMISSION FORMAT
Submit your work as a single document on Moodle using a Word or PDF formats. Please note that Moodle will not accept certain other types of document format for this submission, such as Excel documents.
Calculations can be done via any combination of by hand, on a calculator and using Excel. Combine your solutions into a single document:
● Forexample, if you have done calculations in Excel and you wish to include them in a Word document then copy them from Excel and paste into your Word document.
● Similarly, if you have written answers to the questions by hand then please use scanning software such as Microsoft Lens to scan the written answers and then include these in a Word or PDF document. Details on using Microsoft Lens is available here. The video with instructions is available here.
COVERSHEET
You are not required to submit your work with a coversheet unless you have an ILSP. For students with an ILSP,you will have already been provided with a coversheet. Coversheets cannot be submitted after the deadline,so please make sure you remember to include this.
EXTENSIONS
If you feel that a situation outside of your control has affected your ability to complete your work to a high standard, you can ask for an extension.Extensions are granted for exceptional circumstances only; please note, technical issues, minor illnesses such as a cold, issues with your housemates, etc. are rarely exceptional circumstances.
To request an extension, please contact the LUMS UG Office ([email protected]). The standard length for an extension is up to 3 days, and you must provide evidence. You can request an extension without, but the evidence must follow shortly after.
Extensions must be requested in advance. Therefore, they will not be granted on the day of (or after) the deadline, unless you have been affected by something occurring that day, or you can show there is a legitimate reason why you were unable to request the extension earlier (for example, you were in hospital).
Question 1(25 marks)
Local authority A has made a study of material being recycled per houschold following the introduction of a recycling scheme. Information from other local authorities that
have introduced similar recycling schemes is that recycling material collected each week per household follows a normal distribution with mean 40kg and standard deviation
15kg and is independent over houscholds.It is considered reasonable to assume that the information from the other local authorities is applicable to local authority A.
(a)For a randomly selected houschold whose recycled material is collected by localauthority A calculate the probability that the recycled material collected in a given
(b)A random sample of 100 houscholds is taken and the sample mean recycled
material collected per household is found. Calculate the probability that the
sample mean recycled material collected in a given week is less than 30kg. [7]
(c) The sample mean recycled material of 100 households on a single street is taken
and found to be 30kg. Why is this not necessarily overwhelming evidence that the recycling scheme of local authority A is not working as well as for other local
authorities? [4]
(d)To encourage increased recycling performance, local authority A introduce an
extensive advertising campaign.Following the campaign, the authority collect a
random sample of 1,000 households and find the sample mean recycled material is 41kg. Construct a 95% confidence interval for the mean amount of recycled
material per household in local authority A,treating population standard deviation as known as 15kg. Is there statistically significant evidence of increased recycling
following the campaign? [10]
[25 marks in total]
Question 2 (25 marks)
(a)In a sample of 400 screws manufactured by Lancashire Autoparts Corporation(LAC) there were 12 whose internal diameters were not within the tolerances. Is this sufficient evidence for concluding that the manufacturing process is turning out more than 2% defective screws? Use a hypothesis test at 5% significance level to answer this question and clearly justify your approach. [10]
(b)LAC has added a new machine to its facility at Lancaster to increase production of screws. To compare the efficiency of the new machine compared to the existing machine the plant manager recorded the hourly production output of both machines. He recorded the output on the new machine 8 times whereas on the existing machine he observed the output 9 times.The observed hourly outputs are given in Table1. Using a hypothesis test at 5% significance level determine if we can reject the claim that the mean hourly output on new machine is equal to that of the existing machine.Clearly state your assumptions and the statistical basis for your decision. [15]
New machine Existing machine |
16 10 4 10 14 12 6 8 10 6 4 5 4 7 585 |
Table 1.New vs Existing: hourly production output
[25 marks in total]
Question 3 (25 marks)
A company tests the performance of a random sample of 12 of its production staff before and after the staff undertake a training course. The test scores are
Emplovee A B C D E F G H I J K L
Before 12 26 45 47 48 51 52 55 60 65 68 76
After 30354359474558606766 7079
(a)Explain the difference between dependent(paired)and independent (unpaired) data. [3]
(b)What is the benefit of a hypothesis test using dependent samples over independent
(c)Are these data from independent samples or dependent samples? Justify your answer. [3]
(d)Conduct a hypothesis test at the 5% significance level to determine if the training course improves the performance of the company's production staff? [12]
(e)Is there statistical evidence that the training course improves the performance of the company's production staff? Justify your answer. [3]
[25 marks in total]
Question 4(25 marks)
Metabolic rate, the rate at which the body consumes energy and is an important factor for in studies of weight gain, dieting, and exercise. The researchers believe that the lean body mass (a person's weight, leaving out all fat) has an important influence on metabolic rate. Table 2 contains data on
the lean body mass and resting metabolic rate for 12 women who are participating in the study on dieting. Lean body mass is given in kilograms. Metabolic rate is measured in calories burned per 24 hours.
The dataset 'metabolic rate.xlsx' contains the collected information.
Participant |
Lean Body Mass |
Metabolic Rate |
1 |
36.10 |
995 |
2 |
54.60 |
1425 |
3 |
48.50 |
1396 |
4 |
42.00 |
1418 |
5 |
50.60 |
1502 |
6 |
42.00 |
1256 |
7 |
40.30 |
1189 |
8 |
33.10 |
913 |
9 |
42.40 |
1124 |
10 |
34.50 |
1052 |
11 |
51.10 |
1347 |
12 |
41.20 |
1204 |
Table 2. Metabolic Rate vs Lean Body Mass
a. Calculate the sample correlation coefficient for the data and comment on its value. [2]
b. Construct a linear regression model. [2]
c. Interpret the regression coefficient βi. [3]
d. Plot the data and the estimated regression line. [2]
e. Calculate and interpret the coefficient of determination R2. [3]
f. Perform a hypothesis test at the 5% significance level for the gradient of the regression line and draw conclusions about whether there is evidence for a relationship between lean body mass and metabolic rate. [3]
g. Produce appropriate plots of the regression residuals to assess the assumptions of the regression model. Consider whether there are any patterns in the residuals,
whether they are normally distributed and whether they have constant variance? Do you think all the conditions for inference are met? [5]
h. Produce a 95% confidence interval for the prediction of the metabolic rate if the lean body mass is 45kg [5]
[25 marks in total]
2023-01-19