Q1. A paper is submitted to a clinical journal that describes the use of a new surgical technique on
a patient and reports a successful outcome when the technique is used in the treatment of a single
patient. Which of the following statements best describes the paper?
(a) This paper constitutes good evidence to adopt the new procedure.
(b) This paper is an example of qualitative research.
(c) This paper is an example of a case-control study.
(d) This paper is of no value because it describes the result from a single patient and should not be
published.
(e) All new surgical procedures are first reported in a paper describing the results from the first
attempt.
Q2. In order to test the hypothesis that the dried food fed to cats is responsible for an increased
risk of urolithiasis a study is performed examining the dietary history of a sample of 100 cats
diagnosed with urolithiasis. For each case of urolithiasis two healthy cats of the same age, sex and
breed were also recruited into the study to provide a comparison group and the type of food fed
to these cats was recorded. 80 out of the 100 urolithiasis cats had been fed dried cat food while
only 40 out of the 200 healthy cats had been fed this type of food. Which of the following
statements best describes the findings of this study with regard to the hypothesis being tested?
(a) The prevalence of urolithiasis in cats is 33.3%.
(b) Healthy cats are half as likely to be fed dry cat food as compared to cats with a diagnosis of
urolithiasis.
(c) The odds of a cat with urolithiasis having been fed dry cat food is 8 to 1.
(d) The risk ratio of a cat developing urolithiasis having been fed dry cat food is 4.
(e) The odds ratio of a cat with urolithiasis having been fed dry cat food as compared to a healthy
cat is 16.
Q3. A new serological assay has been produced to diagnose early a neoplastic condition. The test
is assessed using 1000 healthy individuals and 1000 individuals for which there is already a
definite diagnosis for this condition. There are 850 positive results among the individuals who
have the condition and 50 positive results among the healthy individuals. The specificity of the
serological test for diagnosing this neoplastic condition is:
(a) 5%
(b) 15%
(c) 30%
(d) 85%
(e) 95%
Q4. Consumption of alcohol and the smoking of tobacco products are both causal factors in the
incidence of oesophageal cancer. These two risk factors are not independent, but operate
synergistically. If a study was attempting to quantify the risk of smoking in the aetiology of
oesophageal cancer and failed to control for the amount of alcohol consumption which of the
following types of bias would influence the result?
(a) Confounding bias
(b) Design bias
(c) Recall bias
(d) Recruitment bias
(e) Selection bias
Q5. In a study of an endemic infectious disease within the UK cattle population it is determined
that 2% of the population are infected at any single point in time. In another study it is determined
that the average duration of disease is 8 weeks. Using this information what would be your best
estimate for the annual incidence of disease in a herd of 100 cows?
(a) 2
(b) 8
(c) 13
(d) 16
(e) 26
Q6. In a study attempting to provide evidence on the outcomes following hip replacement surgery
a number of data were collected. One variable that was collected was described as “Cause of death
within 30 days following hip replacement surgery using one of two surgical techniques in a topranked hospital”. Which of the following best describes this type of data?
(a) Numerical, continuous
(b) Categorical, ordinal
(c) Categorical, nominal
(d) Numerical, discrete
(e) Categorical, binary
Q7. When making inferences, 95% confidence intervals are considered more informative than pvalues for a variety of reasons. Which one of the statements concerning 95% confidence intervals
given below is NOT true?
(a) They generally indicate whether or not a result is statistically significant at the two-sided, 0.05
level of significance.
(b) They are less open to post hoc analyses (“data-dredging”) than significance tests.
(c) They automatically include the true (population) value of the parameter being estimated.
(d) They convey the uncertainty or imprecision of an estimate.
(e) They incorporate information about the sample size involved.
Q8. A one-sided p-value comparing two groups of randomly sampled data in a well conducted
study is correctly computed to be 0.04. What can be inferred from this study?
(a) The study was adequately powered to detect a meaningful difference between the two groups.
(b) The null hypothesis of no difference between the population means for the two groups has a
4% chance of being true.
(c) A two-sided test on the same data is also statistically significant at 0.05 level of significance.
(d) The alternative hypothesis must be true.
(e) None of the above.
Q9. Which of the following is a valid reason for a leading journal’s statistical reviewer to
recommend rejection of a submitted article describing a randomised controlled trial?
(a) Authors failed to consult a statistician at the correct design stage of the study.
(b) The study was not blinded (those assessing the health outcomes were aware of treatment
group allocation).
(c) The abstract failed to mention a 95% confidence interval for the study’s primary outcome (the
main result).
(d) The study was of adequate size but the primary outcome was not statistically significant.
(e) The randomisation was done in a manner that allowed the researchers to know each patient’s
treatment in advance of allocation.
Q10. “Mesothelioma is incurable, with a median mortality of only eight months after discovery” as
quoted by Stephen Jay Gould in an article entitled “The median isn’t the message”. Which one of
the following comments about newly diagnosed mesothelioma patients is false?
(a) Their mean survival time is greater than the median due to the skewed nature of survival time
distribution.
(b) They may die from a cancer different from mesothelioma.
(c) Half will live for at least 8 months.
(d) Fewer than 75% will have died within 8 months.
(e) None will live for twenty years post-diagnosis.
11.
A study of drinking and oesophageal cancer was undertaken in France, on 205 drinkers
(who drank > 80 mg / day) and 770 non and light drinkers (who drank < 80 mg / day) over two
years. Amongst the non or light drinkers 104 developed cancer, whilst amongst the heavier
drinkers 96 developed the disease. What type of study was undertaken?
(a)
a cross sectional study
(b)
a retrospective study
(c)
an intervention trial
(d)
a prospective study *
(e)
a descriptive study
12.
What is the relative risk from the study in Q3:
(a)
about 3 /10 / 2 years
(b)
about 7 / 100 /2 years
(c)
3.47 *
(d)
70.6%
(e)
33.88%
13.
What is the excess risk in Q11:
(a)
about 3 /10 / 2 years
(b)
about 7 / 100 /2 years
(c)
3.47
(d)
70.6% *
(e)
33.88%
14.
What does individual excess risk mean? CHECK THE OTHERS FOR MORE
DEFINITIONS
(a)
the extra cases of disease in the population attributable to the exposure *
(b)
how many more times exposed subjects are to suffer the disease than those not so
exposed
(c)
the numbers who would need to be exposed to produce an extra case of the disease
(d)
the extra cases of the disease amongst the exposed due to their exposure
(e)
the likelihood of people with the disease being exposed compared to those without
the disease
15.
In question (3) what is the number needed to treat in order to prevent one case of the
disease?
(a)
about 3 people *
(b)
about 100 people
(c)
about 5 people
(d)
about 10 people
(e)
about 1 person
16
An age, gender, and occupation matched prospective study of smoking and cardiovascular
disease (CVD) and lung cancer found the following:
Lung cancer
CVD
Age standardised death rates (per 1000 person years)
RR
Excess risk
32.4
2.20
1.4
2.61
RR = relative risk
What do these results show?
(a)
elimination of smoking would save more deaths from CVD than lung cancer *
(b)
elimination of smoking would save more deaths from lung cancer than CVD
(c)
there is no clear relationship between the risk factor and either event
(d)
there is no statistical significant relationship between the risk factor and cancer
(e)
there is no relationship between smoking and CVD
17.
If the various colleges were listed in alphabetical order what type of scale would this be?
(a)
ratio
(b)
ordinal *8(c) ranked
(d)
cardinal (numeric)
(e)
interval
18.
Under what circumstances would you wish a screening test to be highly specific?
(a)
the disease is highly dangerous at individual patient level *
(b)
treatment and diagnosis are potentially damaging to patients
(c)
the disease is highly infectious
(d)
the disease is prevalent
19.
If a screening test were reported as being highly sensitive (90%) which of the following
would be applicable?
(a)
the test can be regarded as being extremely accurate
(b)
the test identified a high proportion of those who did not have the disease
(c)
out of those whom the test identified as being positive a high proportion were
positive
(d)
of those whom the test identified as being negative there was a high proportion of
subjects who were free of the disease
(e)
the test identified a high proportion of those who had the disease *
20.
test?
Which of the following definitions best describes positive predictive value in a screening
(a)
the test can be regarded as being extremely accurate
(b)
the test identified a high proportion of those who did not have the disease
(c)
the likelihood that a subject who has a positive test actually has the disease *
(d)
of those whom the test identified as being negative there was a high proportion of
subjects who were free of the disease
(e)
the test identified a high proportion of those who had the disease
21.
With given specificity and sensitivity, how does the prevalence of a disease relate to its
predictive value?
(a)
the higher the prevalence the lower the positive predictive value
(b)
the lower the prevalence the higher the positive predictive value
(c)
the higher the prevalence the higher the negative predictive value
(d)
the higher the prevalence the higher the positive predictive value *
(e)
there is no relationship
22.
A sample of 200 subjects were tested for a particular condition, the test had 90% sensitivity
and specificity, with 80% prevalence of the condition what is the positive predictive value of the
test?
(a)
100%
(b)
97% *
(c)
90%
(d)
75%
(e)
50%
23
On the same data with 10% prevalence, and with 90% sensitivity and specificity, what is
the positive predictive value of the test?
(a)
100%
(b)
95%
(c)
90%
(d)
75%
(e)
50% *
24.
A study was undertaken on a sample of 30,000 white furred cats and 60,000 cats with black
fur over 2 years to investigate the development of melanoma in each group. Amongst cats with
white fur 39 cases of melanoma developed whilst amongst the black-furred cats 6 cases developed.
What is the relative risk of melanoma in cats with white fur compared to those with black fur?
(a)
1.2/1000/yr white furred animals
(b)
92.3%
(c)
13 *
(d)
15
(e)
12
25.
In studies what types of bias are minimised by the adoption of random sampling?
(a)
misclassification
(b)
recall
(c)
regression to the mean
(d)
confounding
(e)
selection *
26.
What type of bias (amongst others) is minimised by the adoption of double blind method
(a)
observation or information *
(b)
confounding
(c)
selection
(d)
specificity
(e)
sensitivity
27.
A randomised control trial is planned in a sample of patients to test the effectiveness of a
new intervention compared to the existing treatment of choice. The study plans to adopt a
repeated measure procedure, or paired analysis. What does this mean:
(a)
patients are assigned between the treatment groups randomly
(b)
patients in the new treatment group are given varying levels of the drug
(c)
the same subjects receive each treatment *
(d)
the study is a single blind one
(e)
we can expect equal drop out rates from the two groups
28.
A relative risk of lung cancer (a prevalent condition) in smokers compared to non-smokers
of 13 was computed from a cohort study. If a case control study had been undertaken, and the
relative risk estimated, how would the absolute sizes of the risks compare:
(a)
from the case control study the value of relative risk is 1
(b)
the case control RR would exceed 13 *
(c)
the case control RR would be less than 13
(d)
the case control RR would equal 13
(e)
relative risk cannot be estimated from case control studies
29.
In a prospective study undertaken over a one year period, 39 cases of lung cancer were
found in 30,000 smokers whilst 6 cases of lung cancer were found in 60,000 non-smokers. The
smokers and non smokers had been matched for age and gender. From these statistics, what is the
excess risk of smokers developing cancer compared to non smokers:
(a)
39 / 1000 / year
(b)
6 / 1000 / year
(c)
13
(d)
1.2 / 1000 / year *
(e)
92 %
30.
A serological test has been developed for bovine paratuberculosis and was used on 200
cattle known to be infected with bovine paratuberculosis, based on isolation of Mycobacterium
paratuberculosis from fecal samples, and 300 dairy cattle designated free of disease. In the 200
infected cattle, 120 had a positive test and 80 a negative test. Among the 300 cattle designated free,
30 had a positive test and 270 a negative test. What is the specificity of the test:
(a)
90% *
(b)
80%
(c)
60%
(d)
40%
(e)
10%
31.
In a comparison of 2 vaccines (A and B), dogs were assigned to have either one. After one
year, 32 out of the 2000 dogs that received vaccine A had contracted the disease, and 20 out of the
1000 dogs that had received B had contracted the disease. What was the relative risk of
contracting the disease in dogs receiving vaccine A relative to those receiving vaccine B:
(a)
0.8 *
(b)
1.25
(c)
1.6
(d)
2.0
(e)
3.2
32.
How would you interpret the test results in Q31:
(2 answers of the following will be accepted)
(a)
Vaccine B appears to be more efficacious than A
(b)
There was no difference in effectiveness between these vaccines
(c)
Vaccine A seems more effective than B *
(d)
The results are inconclusive as the sample sizes are small
(e)
Statisticians should get out more *
33
When using a screening test, the positive predictive value of the test is which one of the
following:
(a)
decreases as the prevalence of disease decreases *
(b)
(c)
(d)
(e)
decreases as the specificity of the disease increases
decreases as the sensitivity of the disease increases
decreases as the negative yield of the test increases
relates to the proportion of true negatives to test identified negatives
34.
A serological test has been developed for bovine paratuberculosis and was used on 200
cattle known to be infected with bovine paratuberculosis, based on isolation of Mycobacterium
paratuberculosis from faecal samples, and 300 dairy cattle designated free of disease. In the 200
infected cattle, 120 had a positive test and 80 a negative test. Among the 300 cattle designated free,
30 had a positive test and 270 a negative test. What is the sensitivity of the test:
(a)
90%
(b)
80%
(c)
60% *
(d)
40%
(e)
10%
35.
Chronic infection by the Hepatitis B virus is a major cause of primary liver cancer. In a
large cohort study lasting 5 years investigating the association, 120,000 people were tested for
chronic Hepatitis B infection and 10% were found to be positive. Among the 215 primary liver
cancer cases in the cohort, 183 were positive with HepB. What is the relative risk of primary liver
cancer in those who tested positive for the infection compared to those who were negative?
a.
0.019
b.
0.01495
c.
0.00149
d.
51.49 *
e.
8.6
36.
In the above study what is the excess risk of liver cancer (the individual excess risk)?
a.
15 / 1000 positives per 5 years *
b.
52 / 100 positives per 5 years
c.
0.00149
d.
51.47
e.
8.6
37
In the above study what is the population excess risk of primary liver cancer?
a.
65 / 100 in 5 years
b.
14.95%
c.
13 / 10 in 5 years
d.
15 / 10000 in 5 years *
e.
8.6
38
What are the numbers needed to treat to save one case of liver cancer?
a.
0.019
b.
0.01495
c.
0.00149
d.
51.47
e.
67 *
39.
A cohort study can be described by one of the following:
a.
entry is defined by exposure status *
b.
entry is defined by case status
c.
d.
e.
in one group only the researchers intervene by increasing the natural levels of the
exposure
it is undertaken by analysis of existing data
it is undertaken in one time period.
40.
The following results were found in a case-control study examining the possible effects of
lactation on breast cancer risk. Of the 743 controls (those free of the disease) 387 had never
lactated, whilst of the 751 cases 310 reported having lactated. What is the odds ratio for breast
cancer being associated with lactation?
a.
1.309
b.
0.764 *
c.
2
d.
- 0.26
e.
5
41.
There is strong evidence that cervical cancer is associated with a viral infection, but the risk
of developing this cancer is higher in women who smoke. Which of the following statements is
NOT true in regard to this evidence:
(a) smoking may have a direct influence of the development of cervical cancer
(b) smoking may have an indirect influence on the development of cervical cancer through
the lowering of resistance to viral infection
(c) women who smoke are more likely to develop cervical cancer than those who do not
(d) only women who both smoke and develop an infection are at risk from cervical cancer *
(e) there may be another risk factor in addition to the two considered that is important in the
development of the disease.
42.
The incidence of type 1 diabetes is higher in developed rather than developing countries,
and within developed countries the incidence has been increasing over recent years. One
hypothesis put forward is that an increased frequency of infections in early life is protective
against type 1 diabetes. A study investigating this association recently found the following
results: in the 100 cases of diabetes 40 had attended a day nursery early in life whilst of the 100
controls 50 had not. What measure of epidemiological association can be calculated?
(a)
relative risk
(b)
standardised mortality ratios
(c)
odds ratio *
(d)
sensitivity rate
(e)
specificity rate
43
From Q34 what is the value of the epidemiological measure of association of diabetes
associated with having attended a day nursery?
(a).
1.5
(b).
-0.4
(c).
0.4
(d).
-0.36
(e).
0.666 *
44.
The main purpose of random assignment in a clinical trial is to:
(a)
help ensure that the study participants are representative of the general population
(b)
facilitate measurement of the outcome variable
(c )
facilitate adherence to the intervention
(d)
reduce observer bias
(e)
help ensure participants are comparable on baseline characteristics *
45.
In country X the incidence rate of brain cancer is four times lower in women than in men,
the prevalence is almost the same in both sexes. What could account for this?
(a)
the recovery rate is higher in women
(b)
the death rate is higher for women
(c)
duration of the disease is shorter for men *
(d)
duration of the disease is shorter for women
(e)
the duration of the disease is similar in men and women
46. A study used published data on mobile phone use and nervous system tumours in two
countries A and B. In country A mobile phone use is very restricted, in country B it is frequent.
The incidence of such tumours in A is 2.3/100,000 per year, whilst in B it is 8.6/100,000 per year.
The study concluded that this is evidence that mobile phones cause cancer. Whilst this may be the
case, there are some other possible interpretations that have not been taken into account. Which of
the following is not likely to be a possible source of error?
(a)
populations of different ages
(b)
diagnostic classification of cancer cases
(c)
identification of cancer cases
(d)
recall bias *
(e)
confounding
47.
Which of the following is not a measure of central location?
(a)
the arithmetic mean
(b)
the mode
(c)
the geometric mean
(d)
the median
(e)
the range *
48.
Which of the following is a false statement about medical statistics?
(a)
it provides methods of proving or disproving hypotheses *
(b)
its application it can help establish which of two interventions is better
(c)
knowledge of statistical principles is essential in the efficient design of studies
(d)
statistics can be misinterpreted to give more than one conclusion
(e)
the best time to seek statistical advice is before collecting any data
49.
Which of the following statements is true?
(a)
hypothesis tests can only be carried out on categorical data
(b)
hypothesis tests can only be carried out on 2 by 2 tables of data
(c)
confidence intervals can only be used for larger samples (at least 25)
(d)
different tests are used on paired and unpaired (or independent) categorical
variables *
(e)
the null hypothesis of the Х2 (chi squared) test is that 2 categorical variables are
associated