Assessment 3: Public Health Data Analysis
Weighting: 30 %
Details of task:
This assignment involves the presentation and interpretation of descriptive statistics and statistical test results.
- You have been randomly allocated to 1 of a large number of different datasets from the Crescentville Data Set on Moodle.
- This task will take approximately 10 – 12 hrs to complete.
On completion of this assessment task, you will be able to:
- Demonstrate an ability to present data clearly and interpret its results
- Conduct and show workings where appropriate for various statistical tests
- Describe the epidemiological foundations for obtaining the data
- Ability to generate an interpret results based on various statistical tests and public health tasks
Word limit: This assessment is 2,500 word equivalent with a focus on calculations and reporting.
Format: Your results will be submitted in a question and answer format using a quiz mode on Moodle. This report requires extensive data analysis and interpretation skills.
Submission is final and your attempt can NOT be reopened.
Criteria for marking: Question set and marking guide are available on the unit’s Moodle site
Attempts allowed: 1
Release date: Monday, 2 August 2021, 10:00 AM
Due date: Wednesday 13 October 2021, 10:00 AM
Assessment 3: Public Health Data Analysis
In 2002, arthritis and musculoskeletal conditions were identified as a National Health Priority Area and a major health problem in Australia. Arthritis can have a profound impact on a person’s quality of life and wellbeing due to acute and chronic pain, physical limitations, management of the condition and mental health issues. This can often result in withdrawal from social, community and occupational activities.
According to the Australian Institute of Health and Welfare (AIHW) the burden of disease is (updated 06/05/2020):
- Nearly 1 in 7 Australians have some form of arthritis;
- 3 in 4 Australians over 45 with arthritis have self-reported at least one other chronic condition
- 1 in 2 Australians with arthritis experience moderate to severe pain
- 1 in 5 Australian with arthritis experience high or very high levels of psychological distress Please see the Impact of Arthritis report for more information.
There are many different types of arthritis. This assignment is focused on osteoarthritis.
Dataset: The Council of Crescentville
The Council of Crescentville is interested in investigating factors associated with people with osteoarthritis in their population. They have sent out a tender for the brightest researchers to inform their future public health policies and health promotion interventions.
They have existing historical data, collected from a census index from the Council of Crescentville which has 17,935 residents aged between 6 years to 80 years. Each individual’s data were identified by a six- letter identification code. From the records given on Moodle in the Excel file “Crescentville Dataset.xlsx”, the age group and gender of each person in this population are known. This data is a snapshot in time and there is no post-research data available. This historical data only collected gender in two categories: male and female.
The Council wanted to examine the association between reaction time and physical activity, as these may be affected by osteoarthritis. Therefore, they have conducted a one-off test as part of their health assessments and collected the reaction time of the individuals.
A stratified random sample of 100 Crescentville residents has been obtained. The stratification was based on the age groups and the sample size from each stratum was in proportion to that in the population:
| Age Group | 6-20 | 21-35 | 36-50 | 51-65 | 65-80 |
| % | 22 | 23 | 25 | 19 | 11 |
| Variable | Descriptors |
| Age | Years (collected as date of birth ) |
| Gender | Male (M) and Female (F) |
| Handedness | Left Handed (LH) and Right Handed (RH) |
| Physical activity | Hours |
| Reaction time | Seconds |
| Reaction time: Quick and Slow | Quick and Slow |
Looking at your dataset complete the following questions by entering the answers into your Moodle quiz:
Introduction (3 marks)
It is important to have an understanding of your data and variables in research.
Watch the <Crescentville – overall info> video embedded in the quiz.
Before we get started, let’s ask some preliminary questions.
- Describe the condition under investigation i.e. osteoarthritis.
List 2 risk factors that contribute to the development of osteoarthritis? (3 marks)
Section A: Describing & Summarising Data (21 marks)
It is important to have an understanding of your data and variables in research.
Before we start, we need to understand our sampling method, and what types of variables we’ve got. Then we do descriptive statistics before any complicated analysis.
Watch the <Crescentville – Section A> video embedded in the quiz
- The Crescentville sample was obtained by stratified random sampling with the strata based proportionally on age groups. This type of sampling may be necessary for investigating the average reaction time.
What had to be known to achieve it? (Select one or more correct answers) [3 marks]
- A sampling frame of the entire population, along with their age and the proportions of each sub- group in the population is needed to achieve this stratified sampling.
- Age is not relevant to the condition investigated and therefore will have no effect on reaction time or cognition.
- Stratified sampling allows for sequential order within the sample which ensures that the attribute studied is random.
- Stratified sampling allows for the sampling to be random within each sub-group being investigated (in this case, each age group) – so the proportions of the different age groups are the same in the population and the sample.
- Age is often referred to as “the universal confounder” – so reaction time might be affected by age.
- A sampling frame which divides the population into a set of different coherent areas and randomly selects areas to assess.
- Create a table of variables and type of data by matching two terms: [6 marks]
| Variable | Descriptors | Type of Data |
| Age | Years | |
| Gender | Male (M) and Female (F) | |
| Physical activity | Hours | |
| Reaction time | Seconds | |
| Reaction time: Slow and Quick | Slow (>= 0.31 sec) & Quick (<0.31 sec) | |
| Handedness | Left Handed (LH) and Right Handed (RH) |
- A graph is a really useful way to see how the data is distributed.
Therefore your next step is to:
Draw a graph of reaction time.
Please attach the graph as a file below and in the text box, type the file name only. [5 marks]
- Time to identify the appropriate numerical summaries to describe the typical reaction time of individuals in Crescentville.
What is the mean of the sample? (4 decimal places) [1 mark]
- What is the median of the sample? (4 decimal places) [1 mark]
- Indicate if this statement is True or False in regards to the graph and statistics obtained so far.
“The graph shows a fairly normal distribution, and the values of the mean & median are fairly similar. Hence, the mean is an appropriate statistic to describe reaction time.” [1 mark]
- Pick the 2 appropriate summary statistics you should report regarding the reaction time of the sample of the Crescentville people who are aged 6 – 80 years?
Select one or more: [2 marks]
- Range
- Mean
- Inter-quartile range
- Mode
- Median
- Standard deviation
- We need some more information to continue.
What is the range of your sample? (4 decimal places) [1 mark]
- What is the standard deviation (SD)? (4 decimal places) [1 mark]
Section B: Conducting statistical tests (38 marks: 13 Part 1 & 25 Part 2)
Great news. The Council of Crescentville has found your preliminary results very valuable. However, let’s look at the data closer in this next section.
Watch the <Crescentville – Section B part 1> video embedded in the quiz.
Information for Questions 11 to 16. (13 marks for Section B, Part 1)
The Council of Crescentville has contacted you and is really interested in relationship between physical activities and how this impacts on your reaction time to the test.
Is there a correlation between the physical activity reported and their reaction times?
You are going to need to justify your answer using appropriate graphs, interpreting correlation coefficients and appropriate summary conclusions.
- Therefore your next step is to:
Draw a graph for the variables: physical activity and reaction time.
Please attach the graph as a file below and in the text box, type the file name only. [6 marks]
- What is your line of best fit? (All numbers to 4 decimal places) [1 mark]
- What is the predicted reaction time for someone with 3 hours of physical activity per week? (3 decimal places) [1 mark]
- State your r (correlation) value (4 decimal places) [1 mark]
- State your R2 (coefficient of determination) value (4 decimal places) [1 mark]
- Using your results from this section interpret your data by completing this sentence. [3 marks]
“Overall, there was a [X] correlation between reaction times and physical activity. [Y] in physical activity were correlated with [Z] reaction times of individuals.”
[X] = strong negative; weak negative; weak positive; strong positive
[Y] = increases ; decreases
[Z] = increased; decreased
Well that was an interesting conclusion. Let’s see what else we can look at.
Watch the <Crescentville – Section B part 2> video embedded in the quiz.
Information for Questions 17 to 32. (25 marks for Section B, Part 2)
Do males and females differ in their reaction times?
Over the next few questions you will need to create a summary table and conduct a test of significance (95% CI and p-value) between the males and females to answer if there is a difference between their reaction times. Follow all steps clearly and write a clear conclusion.
Hint: Let’s complete all the steps in hypothesis testing.
- State the Null & Alternative hypotheses[2 marks]
- For the following, match the assumption with how it is met in this test. [4 marks]
- What is the reaction time mean for females? (4 decimal places) [1 marks]
- What is the reaction time standard deviation for females? (4 decimal places) [1 marks]
- What is the reaction time mean for males? (4 decimal places) [1 marks]
- What is the reaction time standard deviation for males? (4 decimal places) [1 marks]
- Calculate the difference in means (Female – Male) (4 decimal places) [1 mark]
- Calculate standard error (SE) (4 decimal places) [1 marks]
- Calculate the degrees of freedom [1 mark]
- What is the T-multiplier? (2 decimal places) [1 mark]
Congratulations. You’ve now got the necessary statistics to calculate the p-value and 95%CI
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