University Epidemiology Assignment: Respiratory Health Study Analysis

This assignment analyzes a study on respiratory health in Aboriginal and Torres Strait Islander children in the Australian Capital Territory (ACT). The student addresses the research question, study design (a two-stage questionnaire survey), and its appropriateness. The analysis covers population, sample size impact, response rates, and potential selection and measurement biases. The assignment explores exposure and outcome variables, measurement of asthma, confounders, and statistical power, including confidence intervals and p-values. The major findings highlight higher respiratory disability but lower atopic illnesses in Indigenous children. The student provides an overall assessment, acknowledging the study's value while critiquing limitations like measurement error and selection bias. The study's quality is limited by the measurement error, lack of statistical power and presence of selection bias.

Running head: Epidemiology 1
Epidemiology
by
Course:
Tutor:
University:
Department:
Date:

Epidemiology 2
1. What is the research question of this study? (2 marks)
What is the prevalence of respiratory symptoms and atopic disease in Aboriginal and Torres
Strait Islander (indigenous) and non-indigenous children in the Australian Capital Territory
(ACT)?
2. What type of design was used to complete this study? Please give as much detail in terms of
the general design as you can. (3 marks)
A two-stage questionnaire survey. Questionnaires are appropriate for a large population because
they are fast and the collected data can easily be compared. They provide quantifiable answers
for a research topic. However, varying responses may make it difficult to analyze.
3. Was the overall study design appropriate for the research question? Please explain your
answer fully. (3 marks)
The two-stage questionnaire design was appropriate for the study because it is free from
researcher bias of the interviewer because the feedbacks are the respondent’s own words.
Moreover, the respondents have sufficient time to provide well thought out answers. Since the
analyzed sample was large, a two-staged questionnaire was appropriate because it enables easy
and effective data collection and the outcomes more reliable.
4. What was the population of interest? (3 marks)
All new entrant primary schoolchildren aged 4–6 years
5. Do you think the sample sizes of the surveys for the two groups of interest have an impact on
the quality of the study? (2 marks)

Epidemiology 3
Yes. The size of the two samples varies significantly. A very small sample size reduces the
power of the study and increases the margin of error which makes the study useless (Faber &
Fonseca, 2014). On the other hand, the sample size for the non-Indigenous group is too large
which complicates statistical tests because they were made to handle samples and not
populations. This increases the analysis power and high tendencies to reject the null hypothesis.
6. Please comment about the response rates of the surveys and how these impact on the quality of
the study. (3 marks)
The response rate for the kindergarten was 80%. A response rate of 80% has high
representativeness of the population and thus there is an assurance that the sample participants
reflect the elements in the general population. This increases the quality of the study because a
high response rate reduces nonresponse bias (Davern, 2013).
7. Please discuss the likelihood of selection bias in this study. Can you think of at least two
possible sources of selection bias in this study? (3 marks)
There is a possibility of selection bias in the parental questionnaire (self-selection). The parents
responsible for selecting the children participants with respiratory symptoms may not select
some of their children due to privacy or they may be impartial in the selection. Secondly, all
children in the ACT identified by the parents were to be included in the study. There is a
possibility of selection bias because all children were to be included and yet there was no
randomization in the selection.
8. What was the primary exposure variable in this study? Please explain your choice of this
variable. (2 marks)

Epidemiology 4
The primary exposure variable is the symptoms of respiratory disease or asthma. This is because
the possible dependent variable is respiratory health and the independent variable is respiratory
symptoms or asthma. Respiratory health is dependent on whether there is asthma or respiratory
symptoms.
9. What were the major outcome variables in this study? (3 marks)
The major outcome variables in the study were parent-reported asthma and four respiratory
symptoms namely recent wheeze, wheezing with colds, dry cough at night without colds and
shortness of breath with exercise.
10. How was the presence of asthma measured in this study (2 marks)? Is there likely to be
measurement error in the way asthma was measured? Please explain. (2marks)
The presence of asthma was measured using parent-reported asthma and four respiratory
symptoms such as recent wheeze with colds or without, dry cough at different times and weather
etc. There are very high chances of measurement error in the way in which asthma was
measured. First, the measurement relied on the parental reported asthma which is subjective
because it will depend on several factors such as the time observed, the environmental
conditions, the expertise etc. Additionally, the recent respiratory symptoms used to measure
asthma could not be standard across the participants. For instance, wheezing with colds could
vary depending on the severity of asthma or the cold itself among other factors.
11. Name two other possible sources of measurement bias in this study? (2 marks)
Other sources of measurement bias include the self-reported parental questionnaire and the
parent-reported asthma symptoms

Epidemiology 5
12. What important confounders were considered (or not considered) in this study? When and
how did the researchers control for confounders in this study (3 marks)
The possible significant confounders included environmental tobacco smoke (ETS) and asthma
symptoms. There were controlled using the ISAAC core question
13. Is the power of the study mentioned in the paper? Do you think there was sufficient power to
answer the research question? (3 marks)
The study doesn’t mention anything to do with the power
14. Are confidence intervals and/or p-values provided in the findings of the study? If they are
provided, can you give some examples and explain what those confidence intervals and/or p-
values values indicate about the significance of the findings? (4 marks)
The study has used confidence intervals and p values. For example, p-values <0.05 were
considered statistically significant. The recent wheeze among kindergarten indigenous children
was had CI of 1.0-2.0, a parent-reported asthma CI 1.3-2.5 etc. confidence intervals enables one
to assess the significance of a study. They show the possible largest and smallest effects that can
occur. The upper and lower limits of the CI provide additional information on how the extent of
the true effect. The narrower the CI the better. P-values are also important in determining the
significance of research results. P-values are used to accept or deny hypothesis tests which are
used to test the validity of an assertion regarding a given population.
15. What were the major findings of this study? Please don’t list all of the findings but
summarise in your own words and in one short paragraph what you consider to be the most
important findings. (5 marks)

Epidemiology 6
The Indigenous children in the ACT experience a high respiratory disability but less of the atopic
illnesses of hay fever and eczema than their counterparts.
16. What is your overall assessment of the value and quality of this study? Please draw on your
previous answers as well as any other additional issues that you feel are important to consider.
Back up all your judgements with evidence and conclude with an overall opinion of how you rate
this work. Please answer this in
300 words or less (6 marks)
The study of value because it shows the most vulnerable children to respiratory diseases and the
predisposing factors. Such findings can be used by hospitals and health ministries to help reduce
the prevalence of respiratory diseases among the most affected population. Moreover, the
findings can be used by the government to help make appropriate changes to the current health
policies to help improve healthcare services. However, the study quality is limited by the
measurement error, lack of statistical power and presence of selection bias.

Epidemiology 7
References
Davern, M. (2013). Nonresponse rates are a problematic indicator of nonresponse bias in survey
research. Health Services Research, 48(3), 905-912.
Faber, J., & Fonseca, L. M. (2014). How sample size influences research outcomes. Dental press
journal of orthodontics, 19(4), 27–29. doi:10.1590/2176-9451.19.4.027-029.ebo