Identifying Types of Study Designs

This document provides descriptions of different study designs and asks readers to identify the type of study being described. It covers various types of studies such as cross-sectional, cohort, case-control, and randomized controlled trials.

Questions
For questions 1 to 6, identify the type of study being described from the descriptions provided (6
marks)
1. A questionnaire was posted to 20,000 Australian adults aged between 18 and 69 years whose
addresses were randomly selected from the electoral roll. They were asked about their marital
status, occupation, education level, and current income.
a. Cross-sectional study
b. Ecological study
c. Prospective cohort study
d. Retrospective cohort study
e. Case-control study
f. Randomised controlled trial
2 In an effort to reduce the incidence of STIs among inner-city residents, researchers undertook a
video-based educational program on condom acquisition among men and women seeking services
at a large sexual health clinic in the South Bronx, New York. A total of 3,348 African-American and
Hispanic men and women patients were randomly assigned to receive: video-based education;
video plus an interactive education session; or usual care.
a. Cross-sectional study
b. Ecological study
c. Prospective cohort study
d. Retrospective cohort study
e. Case-control study
f. Randomised controlled trial
3. A history of alcohol use was obtained from all patients entering a hospital who have
oesophageal cancer and was compared with alcohol use histories of patients with appendicitis
who enter the same hospital.
a. Cross-sectional study
b. Ecological study
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c. Prospective cohort study
d. Retrospective cohort study
e. Case-control study
f. Randomised controlled trial
4. In 2015, an investigator performed a computerised search of records for the 40 community
dental clinics across metropolitan Melbourne to identify children who had attended the dental
service between 2000 and 2005. From these records, he identified children who had fluoride
varnish applied to their teeth and a comparable group not treated with fluoride varnish. After
obtaining ethics approval, the children, were invited to attend for free dental examinations to
detect any evidence of tooth decay.
a. Cross-sectional study
b. Ecological study
c. Prospective cohort study
d. Retrospective cohort study
e. Case-control study
f. Randomised controlled trial
5. What type of study is presented in this graph?
Cervical cancer death rate (per
100,000 person-years)
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Incidence of HPV per 10,000 women
a. Cross-sectional study
b. Ecological study
c. Prospective cohort study
d. Retrospective cohort study
e. Case-control study
f. Randomised controlled trial
6. A group of researchers were interested in the impact of puberty on the development of
mental health problems in adolescents. They recruited 5,000 children in grade 5 from 100
primary schools in the Melbourne metropolitan area and followed them annually for the next
five years. They measured hormone levels and conducted screening test for anxiety and
depression at each follow-up.
a. Cross-sectional study
b. Ecological study
c. Prospective cohort study
d. Retrospective cohort study
e. Case-control study
f. Randomised controlled trial
7. A longitudinal study was conducted with a sample of 2,500 people aged 40 to 69 years. Of
these people, 270 reported that they had diabetes at the start of the study. The measure you
could calculate from the information provided is (1 mark):
a. Point prevalence
b. Period prevalence
c. Cumulative incidence
d. Incidence rate
e. Prevalence rate ratio
8. A study of 26,870 Indian women aged 50-69 years aimed to assess the effects of yoga on hip
fractures in adult Indian women. The study found 849 women reported a hip fracture over the
next five years. The measure you could calculate from the information provided is (1 mark):
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a. Point prevalence
b. Period prevalence
c. Cumulative incidence
d. Incidence rate
e. Prevalence rate ratio
9. Which of the following is a disadvantage of cohort studies? (1 mark)
a. Not suited for the study of common diseases because only small numbers of subjects
would be required.
b. Not suited when the time between exposure and disease manifestation is short, as this
would reduce the follow-up time required.
c. Only allow a single exposure and outcome to be studied
d. Maintaining high rates of follow-up can be difficult.
e. Expensive to carry out because intense follow-up of cases is usually required.
10. Which of the following features should apply to a screening programme (1 mark)
a. There should be a low prevalence of pre-clinical (early stage) disease
b. We don’t need to understand the natural history of the disease as screening will allow us
to study this in detail
c. The disease should be severe, relatively common and perceived as a public health problem
d. There should be a low prevalence of pre-clinical (early stage) disease
e. The test should identify at least 50% of the cases
f. General practitioners need to be able to administer the test.
11. The advantages of Case Control studies are (1 mark):
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a. Relatively quick and cheap to conduct
b. Can investigate a wide range of possible risk factors
c. Useful for very common diseases
d. Can employ expensive or time-consuming tests
e. Both a and b
f. All of a, b, c and d
g. Each of a, b and d
12. In general, screening should be undertaken for diseases with the following feature(s) (1 mark):
a. Diseases with low prevalence in identifiable subgroups of the population.
b. Diseases for which case-fatality rates are low.
c. Diseases that are readily diagnosed and for which treatment efficacy has been shown
to be equivocal in evidence from a number of studies.
d. Disease with a natural history that can be altered by medical treatment.
e. None of the above.
13. If there is an epidemic it means that a disease: (1 mark)
a. Requires a high level of medical intervention
b. Is habitually present in human populations
c. Affects a large number of countries simultaneously
d. Occurs clearly in excess of the expected numbers
e. Is prevalent among animals.
Read this study description and answer the following question (1 mark)
When studying risk factors for Alzheimer’s disease (AD), a form of dementia found mainly in older
people, exposure to head trauma in the past was investigated. Of 100 AD cases, only four recalled
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any head trauma, but of the 100 age-matched controls (without AD), there were 20 people who
remembered some form of trauma to the head.
14. Based on the information provided we can conclude that head trauma does not increase the
risk of subsequent onset of Alzheimer’s Disease The most likely source of error or bias in this
study is:
a. Confounding
b. Selection bias
c. Measurement bias
d. Lack of power
e. None of the above
15. Which of the following is not a possible cause of measurement bias (1 mark):
a. Misclassification of exposure status
b. Misclassification of outcome status
c. Loss to follow-up
d. Recall bias
e. Observer bias
Read this study description and answer questions 16 to 20 (1 mark each)
Researchers in the USA investigated whether rural adults consumed at least five servings per day
of combined fruits and vegetables. They used a survey where a random sample of households was
selected and data were collected from one randomly selected adult in each household. Analysis
revealed that in comparison to non-rural US adults, rural adults were less likely to consume five or
more daily servings of fruits and vegetables (OR=0.861, 95% CI 0.860-0.862). Further analysis
revealed that US rural adults consuming at least five daily servings of fruits and vegetables were
more likely to be female, non-Caucasian, married or living with a partner, living in a household
without children, living in a household whose annual income was > $35,000, and getting at least
moderate physical activity.
16. The outcome of interest in this study is (choose 1)
a. The gender of the study participants
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b. The marital status of the study participants
c. The household annual income of study participants
d. The consumption of fruit and vegetables by study participants
e. Each of a., b., and c. is correct
f. None of the above is correct
17. The study factors of interest include (choose 1)
a. The gender of the study participants
b. The marital status of the study participants
c. The household annual income of study participants
d. The consumption of fruit and vegetables by study participants
e. Each of a, b, and c is correct
f. None of the above is correct
18. The study results were reported as (choose 1)
a. Odds ratios
b. Risk Ratios
c. Prevalence rates
d. Incidence rates
e. Attributable risks
19. The study found that in comparison to non-rural US adults, rural adults were less likely to
consume five or more daily servings of fruits and vegetables. This result should be treated with
caution, as it is likely to be due to chance variability in the data. (choose 1)
a. True
b. False
20. State the reason for your answer to question 19.
As the study result detected that, consumption of vegetables are less among the rural population
and this result might be due to the data variability as sample size was not mentioned. Due to
variability in the sample size, result may differ.
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21. Melbourne has been selected for a major sporting event. The event will run over seven days.
Sporting teams are expected to arrive in Melbourne during the week preceding the start of the
event. A very large number of domestic and international visitors are expected for this event.
You are asked to advise on a health surveillance system particularly to detect outbreaks of
infectious diseases. What are two of the main infectious disease hazards you would be
concerned about? (2 marks)
The two primary concerns for the infectious diseases are dengue and yellow fever. As in this
sporting event, participants will come from different countries, the risk of yellow fever
(generally occurs in South America) and dengue (occurs mostly in urban areas of tropic region)
cannot be avoided.
22. The surveillance system has been designed to collect comprehensive health data for the period
covering the event – that is the data collection will commence when the sporting teams start
to arrive and run until the final day of the event. Is this a good way to design the system?
Why? (3 marks)
This health surveillance system designed to collect the comprehensive health data is a good way
to design this system and in this system, data will be collected during the arrival of sports team
and this process will continued till the end of the event. This strategy is very good as this
continuous monitoring will allow the administrators in identifying and analysing the condition in a
dynamic way. In addition to this, continuous data collection method will allow the early detection
of risks and instant action can be taken for the identified risks. As a result, the disease outbreak
can be prevented.
23. A large-scale, randomized, controlled trial of an educational program to prevent work
associated low back injury found no long-term benefits associated with training. Four
thousand postal workers were randomly assigned to the training versus no training groups,
and analysed using an ‘intention to treat’ approach after 5 years of follow-up (Daltroy et al.
New England J Med 1997 337:5;322-8). The ‘intention to treat’ analysis means that (1 mark):
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a. The analysis compared workers who underwent training with those who did not
undergo training regardless of which group they were randomised to
b. The analysis compared workers who were randomised to training with those who were
not randomised to training regardless of whether or not they were actually trained
c. The analysis excluded workers who were randomised to training but who were not
actually trained
d. The analysis excluded workers who were not randomised to training but who actually
did undergo training
Read this study description and answer questions 24 to 25 (1 mark each)
CONTEXT: A relative paucity of data exist on the possible health effects of using cellular
telephones.
OBJECTIVE: To test the hypothesis that using handheld cellular telephones is related to the risk of
primary brain cancer.
DESIGN AND SETTING: Case-control study conducted in 5 US academic medical centres between
1994 and 1998 using a structured questionnaire.
PATIENTS: A total of 469 men and women aged 18 to 80 years with primary brain cancer and 422
matched controls without brain cancer.
MAIN OUTCOME MEASURE: Risk of brain cancer compared by use of handheld cellular
telephones, in hours per month and years of use.
CONCLUSIONS: Our data suggest that use of handheld cellular telephones is not associated with
risk of brain cancer, but further studies are needed to account for longer induction periods,
especially for slow-growing tumours with neuronal features.
24. Why might hospitals have been chosen as one of the sources of controls for this study?
(choose 1)
a. Hospital based controls are easy, convenient and relatively cheap to obtain
b. Controls who are also hospital patients may be more representative of hospitalised
cases than controls selected from general population
c. Controls are already under medical care and so may be less likely to suffer adverse
effects from participating in the study
d. Controls are confined to hospitals and so are less likely to be lost to follow-up than
controls selected from another source
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e. Answers a. and b. are both correct
f. Answers a., b. and d. are all correct
The study investigated different histological types of brain tumours. The table below shows the
results for glioblastomas.
Cases Controls
Used cellular telephones 29 76
Did not use cellular telephones 215 346
Total 244 422
25. Calculate the appropriate effect measure for exposure to cellular telephones among cases
relative to controls to one decimal place. (1 mark)
Risk ratio= (29/244)/ (76/422)
= 0.6
According to the study, effect measure for exposure to cellular telephones among cases are lower
relative to the control population.
26. You are comparing heart disease rates between two cities. In the first city, the crude incidence
rate is 4 per 1,000 and the age standardised incidence rate is 3.5 per 1,000. In the second city,
the crude incidence rate is 5 per 1,000 and the age standardised incidence rate is 3.5 per
1,000. What do you conclude (choose 1)(1 mark)
a. The age-specific risk of heart disease is higher in the second city compared to the first
b. The age-specific risk of heart disease is lower in the second city compared to the first
c. The second city has an older population than the first city
d. The second city has a younger population than the first city
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27. A study of traffic safety in a large Australian city showed that 61% of those involved in
accidents last year had more than 10 years driving experience, 21% had 6 to 10 years driving
experience and 17% had 1 to 5 years driving experience. Traffic experts concluded that
experience seems to make drivers complacent and careless. Which of the following states why
this conclusion is not justified? (1 mark)
a. The rates are not standardised for age differences
b. The data are incomplete because of unreported accidents
c. A comparison needs to be made with similar data on drivers not involved in accidents
d. No test of statistical significance has been made
e. Prevalence is used when incidence is required
End of assignment questions
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