RECENT ASSIGNMENT

STAT1412 Data Analysis Laboratory
Assignment 1
Semester 2 2014
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Due: This assignment must be submitted electronically using Assignment 1 Link on FLO under Week 7 by 12pm of Friday Week 7. Hard copy submission or submission by email will not be accepted.
Weighting: This assignment (out of 25 marks) comprises a total of 3 questions and is worth 10% of your final assessment mark.
Instructions:
• You MUST comply to Academic Integrity as indicated on the electronic submission. Please note that this is an INDIVIDUAL assignment, not a group assignment. Inappropriate collaboration will be penalized.
• Any data files will be attached to the link provided on the STAT1412 FLO site under Week 4/Assessment/Assignment 1.
• Your submission should contain one (1) file in PDF format with size no bigger than 20 MB.
• You can update your submission for unlimited number of times before the due date.
• Refer to the “Statement of Assessment” pdf document on FLO regarding late assignment penalties.
• Medical extension or extension due to compassionate ground may be granted. Only applications with legitimate reasons will be considered.
• Keep a copy of the submission yourself.

Writing Up Your Assignment....
• Answer all questions in this assignment. Questions should be answered in the order they appear.
• MS-Word (or other typesetting software of your choice) may be used in preparing your assignment submission whenever appropriate which would then being converted to pdf.
• Excel may be used to assist with calculations. Answers must be written in clear English sentences with all appropriate working and/or supporting computer output shown. Raw computer output without explanatory text is unacceptable.
• All graphs and plots must be constructed properly using EXCEL or R. Free-hand sketching will be awarded with NO MARKS.
• Do not include any graphs, plots or tables in the appendix or attachments. Instead, graphs, plots and tables should be resized properly and being included within the appropriate question.
• Titles (or figure captions), axes-labels, legend(s) (if appropriate) and any other necessary details must be included.
• For tables, titles (or captions) and any other necessary details must be included.
• All workings and intermediate answers must be clearly shown.

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Question 1 [Total: 10 marks]


Adapted from Exercise 1.33-1.34 Diabetes and Glucose (Moore et al 2012)
People with diabetes must monitor and control their blood glucose level. The goal is to maintain “fasting plasma glucose” between about 90 and 130 milligrams per decilitre (mg/dl). Dataset glucose.xls contains the fasting plasma glucose of 18 diabetics enrolled in a diabetes control class, five months after the end of the class. The study also measured the fasting plasma glucose of 16 diabetics who were given individual instruction on diabetes control.
(a) Display and describe the distribution of the fasting plasma glucose of 18 diabetics enrolled in a diabetes control class. [3 marks]
(b) Display and describe the distribution of the fasting plasma glucose of 16 diabetics
who were given individual instruction on diabetes control. [3 marks]
(c) Compare the 2 groups using an appropriate graphical method. What are your conclusions? [4 marks]
Marking Criteria: For full marks, you must provide a relevant Excel or R output for your answer AND suitable explanatory text. Marks will be awarded based on the quality of your assessment of the data and how clearly that assessment is communicated.


Question 2 [Total: 11 marks]
We think of DNA as the stuff that stores the genetic code. It turns out that DNA occurs mainly outside living cells, on the ocean floor. It is important in nourishing seafloor life. Scientists think that this DNA comes from organic matter that settles to the bottom from the top layers of the ocean. Phytopigments, which come mainly from algae, are a measure of the amount of organic matter that has settled to the bottom. The file “dna_oceanfloor.xlsx” contains data on concentrations of DNA and phytopigments (both in grams per square metre) in 116 ocean locations around the world. Does the data give good reason to think that phytopigments concentration helps to explain DNA concentration?
(a) Using an appropriate graphical display, describe the relationship between DNA and phytopigments. [2 marks]
(b) Find the sample correlation coefficient between DNA and phytopigments. Comment.

[2 marks]
(c) Fit a least-squares line to the data. [1 mark]
(d) Write down the equation of the line (model) and interpret all parameters in the model. [3 marks]
(e) Predict the DNA concentrations when phytopigments concentration equals to 0.07 gr/m2 and 0.09 gr/m2 respectively. [3 marks]


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Marking Criteria: For full marks, you must provide a relevant Excel or R output for your
answer AND suitable explanatory text. You may calculate by hand in some parts, but you must show appropriate working. Marks will be awarded based on the quality of your assessment of the data and how clearly that assessment is communicated.



Question 3 [Total: 4 marks]
Arsenic is frequently found both in the natural environment and in food. A study of the relationship between arsenic in drinking water and deaths from lung cancer measured arsenic levels in drinking water in 138 villages in Taiwan and examined death certificates to identify lung cancer deaths. The study summary says that “arsenic levels above 0.64 milligram per liter (mg/l) were associated with a significant increase in the mortality of lung cancer in both genders, but no significant effect was observed at lower levels.”
(a) Identify the study type of the above study (observational or experimental). Explain your reasoning. [2 marks]
(b) Identify the explanatory (X) variable and the response (Y) variable of this study. Justify your answer. [2 marks]
Marking Criteria: Correct answers without explanation will yield no marks. For full marks you must provide suitable explanatory text. Marks will be awarded based on how clearly that assessment is communicated.
End of Assignment 1

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