Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

Analysis of cross-sectional studies First, we calculate the mean difference in the early
surgery group which represents the improvement
𝐷𝑖𝑠𝑒𝑎𝑠𝑒𝑑 𝑝𝑎𝑡𝑖𝑒𝑛𝑡𝑠
Prevalence = from baseline = 31 – 63= -32
𝑇𝑜𝑡𝑎𝑙 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛

Diseased patients = incidence x average disease time Second, we calculate the mean difference in the
endoscopy group which represents the improvement
The association between variables can be tested by
from baseline = 42 – 64= -22
the chi-square test.
Third, we calculate the mean difference in the
The comparison of the population subgroups (i.e.
improvement between the two study groups
females vs. males or children vs. adult) can be done
through chi-square test for categorical variables, t- MD = M (EXP) – M (CONT)
test for normally distributed continuous variables, or
MD = -32 – (-22) = -10 points #
Mann Whitney test for non-normally distributed
continuous variables or ordinal variables. When reading a textbook about the
pathogenesis of Diabetes Mellitus, you got the
Analysis of controlled clinical trials idea of testing the efficacy of calcium channel
blockers for the treatment of diabetes mellitus.
[1] Potential patients are screened for eligibility (as per Which of the following steps is the most
the study protocol). appropriate to proceed forward with this possible
[2] Patients who meet the eligibility criteria are asked research topic?
to participate in the study and give a written informed
o Formulating a research team
consent.
o Writing a study protocol
[3] Patients are examined at the o Searching the previous literature
baseline (before receiving the o Making a pilot study
Pre Pre
treatments); pre-treatment
values Which of the following search queries will
retrieve more results on PubMed?
[4] Patients are followed through
o Parkinson's disease [Title]
the study period.
o Parkinson's disease [All fields]
[5] Patients are assessed again at o Parkinson's disease [MESH]
the end of the study (post- Post Post
In a cross-sectional study to determine
treatment evaluation).
the prevalence of depression among CKD
Example: The Effect of Early Surgery vs Endoscopy-First patients, what is the type of hypothesis in this
Approach on Pain in Patients with Chronic study?
Pancreatitis, The ESCAPE Randomized Clinical Trial.
o Directional Hypothesis
JAMA. 2020;323(3):237-247.
o Non-directional Hypothesis
doi:10.1001/jama.2019.20967
Which of the following search
Endoscopy-first
Early surgery engines/databases will be useful to search in the
approach grey literature (unpublished studies and non-
Pre Izbicki-Pain Score Pre Izbicki-Pain Score indexed journals)?
mean 63 (SD=19) mean 64 (SD=16)
o PubMed/Medline
o SCOPUS
o Google Scholar
o Web of Science
Post Izbicki Pain Score Post Izbicki Pain Score
mean 31 (SD=29) mean 42 (SD=32)

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

In order to search PubMed for papers Drag items from the left-hand list into the right-hand
published by Ahmed Negida, which of the list to order them.
following search queries should be used?
a. Writing the Manuscript
o Negida A[author] b. Analysing the study data 1-
o Negida A[au] c. Applying for ethical approval 2-
d. Searching the literature & formulating 3-
o Both
the hypothesis 4-
o None of them e. Study implementation & data collection 5-
f. Planning (writing the protocol) and 6-
Using the appropriate PubMed filters, how
piloting the study 7-
many review articles were published by Negida
g. Publishing 8-
A?
h. Developing the research idea
o 10
o 24 Observational studies are more useful in
which of the following situations?
o 52
o Investigating the efficacy of a drug that is not FDA
Which of the following statements approved
highlight the importance of literature searching?
o Investigating the real-world effectiveness of a drug
o For educational purpose; it allows me to know that is FDA approved
more about a specific topic o Discovering the mechanism of action of a new
o For clinical practice; it can guide me to take drug
evidence-based decisions
A pharmaceutical company (X) has
o For clinical research; it helps me to make use of
decided to evaluate the impact of introducing
the previous research and improve my design
patient support program to patients who are
o All of the above
taking their drug (XX) manufactured by the
company X. The drug XX is already FDA approved
A statement that describes the key results
and is utilized in the market. The study was
that the researchers expect from their study is
designed to compare two groups of patients: the
called .............
first group will include patients who are taking
o Alternative Hypothesis (H1) drug XX and have selected to join the patient
o Null Hypothesis (Ho) support program offered routinely by the drug
manufacturer, while the second group will
The statement that describes the opposite include a control group of patients who are taking
of what the researchers expect from their study is drug XX but did not choose to utilize the patient
called ............. support program offered by the drug
manufacturer. This design is likely to be which of
o Alternative Hypothesis (H1) the following?
o Null Hypothesis (Ho)
o Observational Study
What is the PMID of the article entitled: o Interventional Study
"Intravenous caffeine citrate vs. magnesium
sulphate for reducing pain in patients with acute A pharmaceutical company (X) has
migraine headache; a prospective quasi- decided to evaluate the impact of introducing
experimental study"? patient support program to patients who are
taking their drug (XX) manufactured by the same
o 30112726 company X. The drug XX is already FDA approved
o 28757917 and is utilized in the market. The study was
o 30666295 designed to compare two groups of patients: the
o 16055451 first group will include patients who are taking
drug XX and the company will provide them with
Arrange the following steps of a research a patient support program as part of the research
study study, while the second group will include a

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
control group of patients who are taking drug XX o The external validity
with no further interventions. This design is likely
to be which of the following? How many members should be in the
ethics committee?
o Observational Study
o Interventional Study o At least 3
o At least 5
After company X conducted several o At least 8
clinical trials to prove the efficacy of drug XX, the o There is no specification
FDA has approved the drug in practice. It is
important to continue evaluating real-life Neuropathology. 2019 Sep 15. doi:
effectiveness of drug XX in an observational 10.1111/neup.12601. [Epub ahead of print];
study design because ...... Glioblastoma with tumor-to-tumor metastasis
from lung adenocarcinoma; PMID: 31523853;
o Clinical trials usually include typical patients who
Which of the following research designs best
were selected carefully for the purpose of the trial;
described the above-mentioned article?
other population as old men, pregnant and
breastfeeding women, and patients with Advice: Use PubMed to search for the article and
commodities might not be well-represented in read it if needed.
these studies.
o Case Report
o Patient compliance in real-life is less than their
compliance in clinical trials therefore, the o Case Series
effectiveness of the drug might decrease in o Cross-Sectional Study
practice. o Case-Control Study
o Some side effects might require long term use in o Cohort Study
order to be noticed in the population. o Clinical Trial
o Some side effects are rare and cannot be noticed
in the samples selected for clinical trials; these Interventional (experimental) studies are
rare side effects might occur in practice when the POSSIBLE for all research questions?
drug is used by thousands of patients o Yes
o All of the above o No
o None of the above
A research design that involves
What is meant by a controlled study? introducing an intervention to the patients.
o A study where the investigators are controlling the o Observational Studies
environmental conditions o Clinical Trials
o A study that has a control group
o A study with intervention that requires a remote Blood samples from 1000 Egyptian were
control taken in Cairo. Their blood samples were
o A study where the experiment is done under analysed by PCR to detect HCV viral DNA. The
controlled conditions PCR test was positive for 75 participants
accounting for a prevalence rate of HCV of 7.5%
What is the purpose of randomization? in the included population. This study is best
described as ...............
o Masking the patients so that no one knows about
the drug they are taking o Observational study
o Obtaining two identical groups to balance all o Interventional study (clinical trial)
confounding variables
Blood samples from 1000 Egyptian were
A study with very strict patient selection taken in Cairo. Their blood samples were
criteria is likely to have limitations related to analysed by PCR to detect HCV viral DNA. The
……… PCR test was positive for 75 participants
accounting for a prevalence rate of HCV of 7.5%
o The internal validity

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
in the included population. Which design best permuted block randomization) by using the Web
describes the study? site ‘Randomization.com’.

o Case Report Which of the following designs best

o Cross-Sectional study describe this study?
o Cohort or Case-Control
o Prospective Cohort Study
Aguiar and colleagues designed a study where o Retrospective Case-Control study
patients with type 1 diabetes mellitus (T1DM) o Pragmatic Clinical Trial
were included. For all patients, serum levels of o Explanatory Clinical Trial
glutamic acid decarboxylase antibody (GADA)
were analysed. The authors reported the If the authors present their data as the
frequency of patients with high titre of GADA (or number of correct answers in each condition,
the prevalence of high GADA titre in T1DM). which of the following statistical tests should be
used to compare the ST and DT conditions in
This study is likely to be .............. terms of the number correct answers?
o Cross-sectional study o ANOVA test
o Clinical trial o Paired samples t-test
o Chi-square test
The authors noticed that among patients
with type 1 diabetes mellitus, high prevalence of o Wilcoxon test
high GADA titre was calculated which means that
several T1DM patients have high GADA titre. If If the authors present their data as the
you know that high GADA titre is a pathological median (IQR) of the number of correct answers in
feature associated with epilepsy. Which of the each condition, which of the following statistical
following conclusions can be drawn from the tests should be used to compare the ST and DT
study? conditions in terms of the number correct
answers?
o T1DM causes Epilepsy
o ANOVA test
o T1DM increases the risk of Epilepsy
o Paired samples t-test
o T1DM patients have a relatively high GADA titre
which suggests a possible association with o Chi-square test
Epilepsy o Wilcoxon test
Herold and colleagues published an article in If the authors present their data as the
PLOS one entitled: “Does squatting need mean (SD) of the correct scores in each
attention? -A dual-task study on cognitive condition, which of the following statistical tests
resources in resistance exercise”. In this study, should be used to compare the ST and DT
twenty-four (10f /14m) healthy adults participated. conditions in terms of the number correct
Each participant was asked to visit the answers?
laboratories for two sessions at least 48 hours
apart. At the first session, the participants were o ANOVA test
informed about the experimental procedures and o Paired samples t-test
had to complete the German version of the o Chi-square test
Physical Activity Readiness Questionnaire
(PARQ) which screens for individuals at
o Wilcoxon test
increased health risk when exercising physically.
If the authors enrolled different patients in
During the second visit, the participants
two different groups (1st group: ST and the 2nd
performed a single-task condition (solving a
group: DT) and they present their data as the
cognitive task during standing, [ST]) and a dual-
mean (SD) of the correct scores in each
task condition (squatting while solving a
condition, which of the following types of the t-
cognitive task, [DT]). The conditions were
test should be used to compare the ST and DT
separated by a rest period of ten minutes and
groups in terms of the number correct answers?
conducted in a randomized order (balanced

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
o One-sample t-test Which of the following best describes the
o Paired samples t-test design of this study?
o Independent samples t-test o Cohort study
o Case-control study
Assume that you know that neither of the
number of correct answers nor the mean heart o Phase I clinical trial
rate is a normally-distributed continuous o Explanatory randomized-controlled trial
variable, and the authors want to evaluate the o Pragmatic randomized-controlled trial
correlation between the participants’ mean heart
rate and the number of correct answers. Which of In this study, freedom from atrial
the following types of correlation coefficients can fibrillation, flutter, or tachycardia at 12 months
be used? was observed in 84 of 148 (56.5%) of those
undergoing pulmonary vein isolation alone and in
o Pearson correlation only
111 of 154 (72.1%) of those undergoing
o Pearson correlation & Spearman correlation
pulmonary vein isolation plus renal denervation.
o Pearson correlation & Kendell tau correlation Calculate the risk ratio with the corresponding
o Spearman correlation & Kendell tau correlation 95% CI.

In the dual task condition, the correlation ..The solution..

between the participants’ mean heart rate and the EXP CONT
number of correct answers was found to be
+ Event 111 84
r=0.36 and P=0.44. How these results are
interpreted? - Event 43 64

o The number of correct answers was positively Total (n) 154 148
correlated with the mean HR of the participants
o The number of correct answers was negatively RR =
111/154
= 1.26
84/148
correlated with the mean HR of the participants
2 1 1 1 1
o The number of correct answers significantly SE of lnRR= √ + − − = 0.238
111 84 154 148
correlated with the mean HR of the participants
95% CI = exp (lnRR ± 1.96 x SE of lnRR)
o The number of correct answers did not significantly
correlate with the mean HR of the participants 95% CI = exp (0.238 ± 1.96 x 0.087)
95% CI = exp (0.238 ± 0.171)
Unlike clinical trials on diseased patients, = exp (0.067) to exp (0.410)
the present study involved healthy participants, = 1.069 to 1.506
therefore, informed consents from the study
NOTES
participants will not be required.
Ln is the inverse function of exponential function
o True ln(x) = log e(x) = y
o False The e constant or Euler's number is e ≈ 2.71828183

Steinberg and colleagues conducted a study to What does the RR represent?

determine whether renal denervation when added
to pulmonary vein isolation enhances long-term o RR = rate in the CONTROL / rate in the EXP
antiarrhythmic efficacy. Patients were o RR = rate in the EXP / rate in the CONTROL
randomized to either pulmonary vein isolation
alone (n = 148) or pulmonary vein isolation plus If the RR was 1.26 with 95% CI from 1.06
renal denervation (n = 154). The primary end point to 1.5. This RR is likely to have which of the
was freedom from atrial fibrillation, atrial flutter, following P values?
or atrial tachycardia at 12 months. Secondary end o P=0.6
points included procedural complications within
o P=0.06
30 days and blood pressure control at 6 and 12
months. o P=0.006

What is the interpretation of this RR?

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
o Renal denervation added to catheter ablation, o The questionnaire was not validated in the
compared with catheter ablation alone, population
significantly increased the likelihood of freedom o The authors were highly selective of the population
from atrial fibrillation at 12 months o The sample was not taken in a random method
o Renal denervation added to catheter ablation,
compared with catheter ablation alone, For a 5-year randomized-controlled trial
significantly decreased the likelihood of freedom on patients with progressive neurodegenerative
from atrial fibrillation at 12 months disease, which of the following methods will NOT
be preferred to supply the data of missing
Which of the following is a patients for the intention-to-treat analysis?
methodological limitation of this study?
o Multiple imputations
o Lack of a control group o LOCF analysis
o Lack of randomization o Analysis of the worst- & best-case scenarios
o Lack of appropriate sham control intervention
Which of the following interventions
Futier and colleagues conducted a randomized- would be suitable for the control group of a
controlled trial to evaluate the effect of randomized controlled trial on a topical agent for
hydroxyethyl starch 130/0.4 compared with 0.9% psoriasis?
saline for intravascular volume expansion on
mortality and postoperative complications after o Observation group (no intervention)
major abdominal surgery. o Placebo control
o Vehicle control
Among the 826 patients enrolled, 775
o Sham control
(94%) completed the trial. Is this incompletion
rate likely to affect the internal validity of the Which of the following interventions
study? would be suitable for the control group of a
o Yes randomized controlled trial on the effect of
magnetic transcranial stimulation for Parkinson’s
o No
disease?
The composite of death or major o Observation group (no intervention)
postoperative complications at 14 days after
o Placebo control
surgery occurred in 139 of 389 patients (36%) in
o Vehicle control
the HES group and 125 of 386 patients (32%) in
the saline group. Calculate the RR and the o Sham control
corresponding 95% confidence intervals.
“Gender: Male or Female”, which type of
data is this variable?

o Quantitative
A cross-sectional survey will not be
internally valid in which of the following o Qualitative
situations? [select two]
“Age”, which type of data is this variable?
o Response rate is lower than 65%
o Quantitative
o The questionnaire was not validated in the
population o Qualitative

o The authors were highly selective of the population “Age group”, which type of data is this
o The sample was not taken in a random method variable?

A cross-sectional survey will not be o Quantitative

externally valid in which of the following o Qualitative
situations? [select two]

o Response rate is lower than 65%

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

If the stages of a malignant type of cancer P value represents ……………

are named as I, II, III, IV, and V. This type of data
o Type 1 error
is considered to be …………….
o Type 2 error
o Nominal
o Ordinal P value represents …………….
o Numeric o Alpha error
o Beta error
What is the meaning of a statistically
significant test result?
In a clinical trial to test the efficacy of drug
o P value is less than 0.05 (X) in lowering the ABP, the probability of
o The probability, that the null hypothesis is correct, obtaining reductions in ABP within the sample
is below 5% population when the drug (X) is not actually
effective in the HTN population (P value more
o The resulting effect/outcome is of clinical
than 0.05). This scenario describes which type of
importance in clinical practice
errors?
o There is a low possibility that the resulting
outcome is due to chance (below 5%) o Type 1 error (alpha error)
o Type 2 error (beta error)
What is the meaning of a clinically
significant test result? In a clinical trial to test the efficacy of drug
(X) in lowering the ABP, the probability of
o P value is less than 0.05
obtaining statistically significant reductions in
o The probability, that the null hypothesis is correct,
ABP (P value less than 0.05) but this difference
is below 5%
does not exist clinically in HTN population. This
o The resulting effect/outcome is of clinical scenario describes which type of errors?
importance in clinical practice
o There is a low possibility that the resulting o Type 1 error (alpha error)
outcome is due to chance (below 5%) o Type 2 error (beta error)

What does it mean when you calculate a Which of the following tends to happen
95% confidence interval? when you increase the sample size of the study?

o The process you used will capture the true o SD decreases

parameter 95% of the time in the long run o Statistical power increases
o You can be “95% confident” that your interval will o Precision increases
include the population parameter o Confidence intervals become narrower
o You can be “5% confident” that your interval will o All of the above
not include the population parameter
o All of the above Which of the following measures of
central tendency will always change if one value
In clinical research, we tend to use ___% of the population becomes extreme?
confidence intervals
o Mean
o 90% o Median
o 95% o Mode
o 99%
Which of the following is the best
Which of the following occasions might descriptive statistics for normally distributed
explain a relatively wide standard deviation (SD)? data?

o The sample size (n) is relatively small o Mean (Standard deviation)

o The measured variable is not homogeneous o Median (interquartile range)
(widely variable) in the sample population o Range
o Both of the above

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

Which of the following is the best Negida and colleagues conducted a study on the
descriptive statistics for non-normally distributed efficacy of intervenors caffeine for the treatment
data? of acute migraine pain. Data of the VAS pain
score of the study participants at baseline, after
o Mean (Standard deviation)
one hour, and after two hours are presented in the
o Median (interquartile range) figure below.
o Range

In a randomized placebo-controlled trial,

researchers tested the efficacy of Liraglutide for
improving sleep quality and health-related quality
of life in patients with type II diabetes mellitus.
Results showed that compared to the placebo
group, patients taking Liraglutide had more
improvements in the sleep quality questionnaire
as well as the HRQoL questionnaire (P=0.02, and
P=0.09, respectively). Which of the following
interpretations are correct?

o Liraglutide can significantly improve the sleep

quality of T2DM patients
o Liraglutide can significantly improve the health-
related quality of life of T2DM patients
o Liraglutide did not significantly improve the sleep
quality of T2DM patients
What is the type of the attached figure?
o Liraglutide did not significantly improve the health-
related quality of life of T2DM patients o Bar chart
o Histogram
Based on the previous question, the
o Box plot
statistically significant improvement (P=0.02) in
sleep quality over placebo indicates that this o Scatter plot
improvement is important for clinical practice and o Forest plot
will be useful for patients. o Funnel plot

o True Match the letters mentioned in the Figure

o False (above) with the corresponding statistic values

How do you interpret a P value of 0.05? A 1st Quartile

o This P=0.05 indicates a statistically significant B Maximum
effect C Range
o This P=0.05 indicates a statistically insignificant D Minimum
effect
E 2nd Quartile (median)
o The most accurate interpretation of this borderline
From A to E IQR
P value requires examining the 95% CI of the
effect size From B to D 3rd Quartile

Based on question no.19, which of the In order to compare the VAS scores at
following 95% CI indicates statistically significant baseline vs. after one hour of caffeine
reductions in ABP? administration, which of the following statistical
tests should be used?
o 95% CI [5.00 to -20.0]
o 95% CI [0.00 to -20.0] o Student t-test
o 95% CI [-0.01 to -20.0] o ANOVA test
o Wilcoxon test

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
o Mann-Whitney test malignant cancer, which of the following tests is
appropriate to use?
In order to compare the improvements in
VAS scores between males vs. females in this o Student t-test
study, which of the following statistical tests o Mann-Whitney test
should be used? o Wilcoxon test
o ANOVA test
o Student t-test
o Chi-square test
o ANOVA test
o Wilcoxon test The ability of a diagnostic test to classify
o Mann-Whitney test participants with the disease is called ……….

In Egyptian population, assume that the o Sensitivity

probability of finding an HCV patient is 1% while o Specificity
the probability of finding a diabetic patient is o Accuracy
10%; assume also that both HCV and diabetes are
INDEPENDENT diseases. Calculate the The ability of a diagnostic test to classify
probability of finding a diabetic patient with HCV participants without the disease is called ……..
(both diseases) in the Egyptian population.
o Sensitivity
o Specificity
o Accuracy
Which of the following tests is a non-
parametric test? Pearson correlation (r) measures ……...
o Student t-test o The correlation between two numerical variables
o ANOVA test o The tendency of two numerical variable to
o Kruskal-Wallis test increase, decrease, or inversely change together
o Both of them
Which of the following is correct about
the student t-test? Standard error is used to measure ………
o It is a parametric test o The extent to which individuals vary among each
o It is used to compare means of two groups other in the sample
o Both of the above o The extent to which a sample mean is likely to
differ from the population mean
Which of the following is correct about o The normal distribution of scores around the mean
the ANOVA test?

o It is a parametric test Matta and colleagues conducted a randomized

controlled trial to assess the systemic absorption
o It is used to compare means of > two groups
and pharmacokinetics of the 6 active ingredients
o Both of the above (avobenzone, oxybenzone, octocrylene,
homosalate, octisalate, and octinoxate) in 4
In order to compare the mean depression
sunscreen products under single- and maximal-
scores between patients at different stages of a
use conditions. Participants were randomized to
malignant cancer, which of the following tests is
1 of 4 sunscreen products, formulated as lotion
appropriate to use?
(n = 12), aerosol spray (n = 12), nonaerosol spray
o Student t-test (n = 12), and pump spray (n = 12). Sunscreen
o Mann-Whitney test product was applied at 2 mg/cm2 to 75% of body
surface area at 0 hours on day 1 and 4 times on
o Wilcoxon test
day 2 through day 4 at 2-hour intervals, and 34
o ANOVA test
blood samples were collected over 21 days from
each participant. The primary outcome was the
In order to compare the percentages of
maximum plasma concentration of avobenzone
depressed patients at different stages of a
over days 1 through 21. Secondary outcomes

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
were the maximum plasma concentrations of o Mann-Whitney U test
oxybenzone, octocrylene, homosalate, octisalate,
and octinoxate over days 1 through 21. For Which of the following statistical
avobenzone, the overall maximum plasma measures is not affected by outliers?
concentrations were 7.1 ng/mL (coefficient of
o Standard deviation
variation [CV], 73.9%) for lotion, 3.5 ng/mL (CV,
o Variance
70.9%) for aerosol spray, 3.5 ng/mL (CV, 73.0%)
for nonaerosol spray, and 3.3 ng/mL (CV, 47.8%) o Interquartile range
for pump spray. o Range

What is the type of this clinical trial? Dr. Negida worked on a clinical trial of Deep Brain
Stimulation for Patients with Parinson’s disease.
o Pragmatic clinical trial
Data about the UPDRS score at baseline and after
o Explanatory clinical trial 6 years were plotted in the figure shown below.

How is the coefficient of variation What is the name of this figure? When
calculated? should it be used? What is the name of this
relationship? What is the direction (positive or
Solution
negative) of this relationship?
CV is calculated as the ratio between the standard
deviation to the mean

In-which of the following conditions

investigators might accepting a false null
hypothesis?

o Selection bias
o Chance
o Alpha error
o Beta error
o Probability testing
o Significance testing
If both the UPDRS score at baseline and
The standard deviation of a sample of 100 after 6 months are normally distributed. Which of
observations equals 64. The variance of the the following correlation measures should be
sample equals ……... calculated?

o 8 o Spearman
o 10
o Pearson
o 6,400
o 4,096 o Kendall tau
o None of the above
Assume that the correlation between the
UPDRS scores at baseline and 6 months was
Dr. Negida is conducting a study to
statistically significant. In order to test whether
evaluate patient attitudes towards the
baseline scores can predict the 6-month score,
involvement of medical students in their physical
which of the following types of regression
examination. Participants were asked to rate their
analysis should be conducted?
attitudes using Likert-scale. With the aim to
compare the ratings of male vs. female patients, o Linear regression
which of the following tests should be used? o Binomial regression
o ANOVA o Logistic regression
o Chi-square test o Cox regression
o T-test for independent sample means

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

Negida and colleagues conducted a study to In order to compare the survival between
determine the diagnostic accuracy of 3 the two groups (high BRG1 expression group vs.
biomarkers in the diagnosis of traumatic brain low BRG1 expression group), which of the
injury in suspected individuals. following tests can be used?

Which design best describes this study? o The Log-Rank Test

o The Tarone-Ware Test
o Cohort study
o The Wilcoxon-Gehan-Breslow Test
o Case-control study
o All of the above [the correct answer]
o Diagnostic Test Accuracy study
The log-rank test showed the following
The diagnostic accuracy of the
results (chi-square=8.11, P=0.0044). What is the
biomarkers was presented as the figure shown
interpretation of these findings & the curve?
below. What is the name of this curve?
o The biomarker has a protective effect; patients
with high BRG1 expression are more likely to
survive compared to those with low BRG1
expression.
o The biomarker has a bad effect; patients with low
BRG1 expression are more likely to survive
compared to those with high BRG1 expression.
o No statistically significant association between
BRG1 expression and patient survival

A non-parametric test to compare the

arterial blood pressure of two matched group of
patients is ………...

o Paired-t-test
o Wilcoxon test
o ANOVA test
Which of the biomarkers (A, B, or C) have
the highest diagnostic accuracy and why? Which of the following is a better statistic
to indicate statistical significance?

Ibrahim and colleagues conducted a study to o P value

determine the role of the expression of some o Confidence intervals
colon cancer biomarkers on patient survival. The
following diagram was drawn to represent patient Chi-square test is used to ……
the time-to-event data of the number of patients
o Evaluate the association between two categorical
who survived over time.
variables (i.e. association between gender and
What is the name of this diagram? smoking status)
o Compare a categorical variable between two
groups (i.e. number of smokers in males vs.
females)
o Both of them
o None of them

Which of the following methods can be

used to test data-normality?

o QQ plot
o Frequency distribution curve
o Kolmogorov Smirnov test

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
o Shapiro Wilk test drug Z will be enrolled and followed up for one
year while the events of Y are recorded. The
If the mean difference in IQ between sample size calculation (SSC) for this study will
group A and group B is +10 with a standard error be based on which of the following scenarios [as
of 2. Calculate the corresponding 95% confidence explained by Dr. Negida].
intervals.
o SSC based on prevalence rate
Advice: 95% CI = Mean ± 1.96 x SE o SSC based on correlation
o SSC of cohort studies (two proportions)
Which of the following graphs can
o SSC of superiority clinical trials (two means)
represent the variable: Gender (the percentages
of males and females in the study)?
Issa and colleagues run a randomized controlled
o Histogram trial to compare Early Surgery vs Endoscopy-
o Pie chart First Approach on Pain in Patients with Chronic
Pancreatitis. The primary outcome was pain,
o Scatter plot
measured on the Izbicki pain score. Secondary
Which of the following statistical powers outcomes were pain relief at the end of follow-up;
indicate that the study is underpowered? number of interventions, complications, hospital
admissions; pancreatic function; quality of life
o 99% (measured on the 36-Item Short Form Health
o 85% Survey [SF-36]); and mortality.
o 80%
For this study to have enough statistical
o 50%
power, sample size calculation should be done [at
least] based on which variables?
Which of the following is not a type of the
probability sampling methods? o Izbicki pain score
o Simple random sampling o Pain relief at the end of follow-up, number of
interventions, complications, hospital admissions,
o Stratified random sampling
pancreatic function, quality of life [SF-36], and
o Convenience sampling
mortality
Which of the following is not a type of the o All of the above
non-probability sampling methods?
The authors wrote “Data collection was
o Systematic random sampling done in Istanbul University Hospital, Turkey”.
o Clustered multistage random sampling This sentence contains which of the following
o Snow-ball sampling mistakes?
o Judgmental sampling o It is better to use the active voice
o A and B o Data collection should be presented as a verb
o C and D o Both of them

Underpowered studies are not ethical. What are the authorship criteria used by
Why? the ICMJEs?
o They do not generate much knowledge while
exposing the patients to risks
o The benefits do not outweigh the risks of the study The decision whether to publish the
o They waste time & resources manuscript or not is taken by?
o All of the above o The editor
o The reviewer
X and colleagues aim to determine the
o The editorial assistant
incidence of the adverse event (Y) after the
treatment with drug (Z). They planned a single
arm observational study where patients taking

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training

For standard reporting of the randomized

controlled-trials, it is advised to follow which of
the following statements?

o PRISMA statement
o CONSORT statement
o STROBE statement
o STRAD statement
o CARE statement

For standard reporting of case reports, it

is advised to follow which of the following Why was the first but not the second
statements? article authored by PLOS ONE editors?

o PRISMA statement
o CONSORT statement
o STROBE statement Select the appropriate judgement about random
sequence generation for the following scenarios:
o STRAD statement
o CARE statement

For standard reporting of the diagnostic “Randomisation was done with a

test accuracy studies, it is advised to follow computer-generated sequence and was stratified
which of the following statements? by centre, and sequential minimisation with a
factor of 85% was used to avoid imbalance in
o PRISMA statement
treatment”
o CONSORT statement
o STROBE statement o High risk
o STRAD statement o Low risk
o CARE statement o Unclear risk

For standard reporting of the systematic “Randomization was performed through a

reviews and meta-analyses, it is advised to follow centralized interactive voice response system”
which of the following statements? o High risk
o PRISMA statement o Low risk
o CONSORT statement o Unclear risk
o STROBE statement
“Randomisation was conducted using an
o STRAD statement
interactive voice-response system managed by
o CARE statement the Robertson Centre for Biostatistics, University
of Glasgow”.
For standard reporting of the
observational studies, it is advised to follow o High risk
which of the following statements? o Low risk
o PRISMA statement o Unclear risk
o CONSORT statement
Which of the following checklists should
o STROBE statement be used to assess the risk of bias
o STRAD statement (methodological quality) in the randomized-
o CARE statement controlled trials?

You found the following search results on o Cochrane ROB 2 tool

PubMed; What is the meaning of the circled o ROBINS-II
terms? o Newcastle Ottawa Scale

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 Negida’s Workbook of Clinical Research Skills – A supplement of Negida’s Clinical Research Training
o QUADAS-2 o Source of evidence-based practice
o All of the above
Which of the following checklists should
be used to assess the risk of bias All studies included in the systematic
(methodological quality) in the non-randomized review can be introduced to a meta-analysis
trials? model?
o Cochrane ROB 2 tool o Yes
o ROBINS-II o No
o Newcastle Ottawa Scale
o QUADAS-2 A clinical trial with 15% of missing
participants is likely to have a high risk of …..
Which of the following checklists should
o Selection bias
be used to assess the risk of bias
o Performance bias
(methodological quality) in the diagnostic test
accuracy studies? o Attrition bias

o Cochrane ROB 2 tool Publication bias is likely to affect ……

o ROBINS-II
o Large studies with negative results
o Newcastle Ottawa Scale
o Small studies with negative results
o QUADAS-2
o Small studies with positive results
Which of the following checklists should o Large studies with positive results
be used to assess the risk of bias
In order to overcome publication bias,
(methodological quality) in the observational
which of the following should be done?
studies?
o Search databases of grey literature
o Cochrane ROB 2 tool
o Identify unpublished studies
o ROBINS-II
o Contact experts to ask about potential studies
o Newcastle Ottawa Scale
o Adjusting the analysis using the “trim and fill”
o QUADAS-2
method if publication bias exists
Which of the following, when properly
The flow diagram of the study selection in
done, has the highest level of evidence?
the systematic review is presented as …..
o Phase III randomized-controlled trial
o CONSORT flow diagram
o Systematic Review
o PRISMA diagram
o Meta-analysis
The flow diagram of the participant
Central allocation of the study
selection in the randomized controlled trial is
participants reduces selection bias by the
presented as …..
allocator?
o CONSORT flow diagram
o Yes
o PRISMA diagram
o No
An open label clinical trial might have low
Some surgeries do not allow blinding.
risk of bias in which of the following conditions?
How to overcome the performance bias in these
studies? o The outcome of interest is not likely to be affected
by blinding
o The intervention does not allow for blinding,
Advantages of the systematic review are however, the outcome evaluation was done by
independent blinded raters
o Reproducible o Both of them
o High-evidence

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