RES5115 Research Preparation: Principles and Approaches - Quantitative Assignment

QUESTION 1 [25 MARKS]

A study was conducted to investigate the effects of short-term treatments with growth hormone (GH) on biochemical markers of bone metabolism in men with idiopathic osteoporosis. Subjects ranged in age from 32 to 57 years. Among the data collected were serum concentrations of insulin-like growth factor binding protein- 3 at 0 and 7 days after the first injection and 1, 4, 8 and 12 weeks after the last injection (i.e. post-treatment) with GH. The serum concentration (ng/dL) data for 116 men are given in the Excel file “Serum.xlsx”.

TASK 1 - SELECTING A SUB-SAMPLE

• Open the Serum.xlsx data file as shown.
• Click on the “Data” tab and then run the “Data Analysis” tool pack.
• Select Random Number Generation and click OK.
• Select “Uniform” in the drop-down menu next to “Distribution”. Then fill out the other boxes as shown. In the box corresponding to “Random Seed”, make sure you type the last two digits of your student ID here. This will ensure the set of random numbers is unique to you (unless someone else shares the same two numbers).
• You should now be able to see 116 random numbers in Column H. Take note that your numbers will be different to those shown here.
• Highlight all the data in from Columns A to H using the mouse/keyboard. Then click on and select Custom Sort...
• Now click on underneath Column  Sort by and select (Column H). Make sure that under Order, it is set to Smallest to Largest. Then click OK.
• The data are now sorted according to Column H. Again, note that what is shown here is very likely to be different to what you will have. Now, select the first 60 observations (i.e. Rows 2 to 61) from Columns A to G and copy this sub-sample across to SPSS. These observations form the dataset that you will be working with for this question.

TASK 2 – ANALYSING THE DATA

1. Use SPSS and generate the necessary summary statistics and figures to describe the serum concentrations 0 and 7 days after the first GH injection. Proper interpretation of these output in the context of the problem is expected.
2. Use the appropriate test in SPSS and determine whether the GH treatment had any significant impact on serum concentration 7 days after the 1st injection. You will need to comment on the nature and extent of these differences (if any). Hypothesis statements are not necessary.
3. Confidence intervals should be presented and interpreted whenever possible.
4. All relevant assumptions associated with your chosen test must be verified.
5. Repeat steps (i) – (iv), but in this instance compare the serum concentrations 1, 4, 8 and 12 weeks after the last GH injection (i.e. post-treatment). If the initial analysis suggests a difference, you will then need to perform a post hoc test to determine where the difference(s) lie. Hypothesis statements are not necessary.
6. Based on the outcomes of the two analyses, comment on the short-term and post-treatment effect of GH treatment on serum concentrations.