THG37-001
Match the features related to various study designs.
i. Exposure status known in the beginning and look for outcome | | | i. | Cross-sectional study | |
v. No deliberate intervention | | | v. | Experiment | |
Answer
Features related to various study designs matched.
| i. | Exposure status known in the beginning and look for outcome | iv. | Cohort study | ||||
| ii. | Intervention is under the control of investigator | v. | Experiment | ||||
| iii. | Look for exposure and outcome simultaneously | i. | Cross-sectional study | ||||
| iv. | Outcome known in the beginning and look for exposure status | ii. | Case-control study | ||||
| v. | No deliberate intervention | iii. | Observational study | ||||
THG37-002
Mention the best study design to answer each of the problems.
i. Prevalence of vitamin A deficiency |
v. Spectrum of clinical features of a rare genetic disorder |
Answer
The best study design to answer each of the problem.
| i. | Prevalence of vitamin A deficiency | i. | Cross-sectional survey | ||||
| ii. | Clinical course of Zika virus infection | ii. | Cohort study | ||||
| iii. | Efficacy of ranitidine against omeprazole in acid peptic disease | iii. | Double-blind RCT | ||||
| iv. | Usefulness of procalcitonin in the diagnosis of neonatal sepsis | iv. | Descriptive study | ||||
| v. | Spectrum of clinical features of a rare genetic disorder | v. | Case series | ||||
THG37-003
Fill in the blanks related to classification of the study design, as applicable.
Answer
Classification of the study designs filled completely
THG37-004
In a study to assess the vitamin A deficiency in a school, the calculated sample size of 250 children to be collected from the total of 1,000 school children. They were numbered 1 through 1,000. To select the first child, entire 1,000 children were divided (1,000/250) and arrived 4. From the first 4 children, the number 3 child was selected at random as the first in the sample. Then the subsequent children selected were number 7 (3 + 4), number 11 (7 + 4), and so on to complete the required 250 children for the study.
a. What is the procedure we are describing here?
b. What is this method called?
c. What does the number “4” represent?
d. What is the major advantage of this method?
e. What is the major disadvantage of this method?
Answer
| a. | Sampling technique |
| b. | Systematic random sampling (SyRS) |
| c. | Sampling interval |
| d. | Easy to carry out, once the sampling interval is arrived. |
| e. | Fails to give adequate representation to different segments of the population. |
THG37-005
Q37.5
a. What does above image show?
b. What is the purpose of this?
c. What does the X-axis represent?
d. What do the dots along the curve represent?
e. How is interpretation done?
Answer
| a. | Receiver operative characteristic (ROC) curve |
| b. | The purposes are: |
| • | Changes in sensitivity and specificity for a single test with many cutoffs |
| • | Used to choose the optimal cutoff that minimizes the percentage of false-positive and false-negative results |
| • | Compares the performance of different tests used to diagnose the same disease |
| c. | 1—Specificity |
| d. | Various cutoffs against their respective Sensitivity and 1—Specificity |
| e. | Cutoff with maximum area under curve is the ideal cutoff which will have maximum possible sensitivity/specificity and least possible false-positives and false-negatives |
THG37-006
Q37.6
a. What does above image show?
b. What is the purpose of it?
c. What are the three vertical columns of the readings?
d. How is the interpretation done?
e. What is the rough outcome indicated by the arrow in above image?
Answer
| a. | Fagan’s nomogram |
| b. | Quick way of arriving at pretest probability |
| c. | First column—pretest probability, second column—likelihood ratio, and third column—post-test probability. |
| d. | The line intersecting the respective pretest probability and likelihood ratio points toward the post-test probability for those values |
| e. | Post-test probability of 59% |
THG37-007
Two clinicians examined the fundus for retinopathy in 100 children. Both clinicians concurred for retinopathy in 46 children and no retinopathy in 32 children. For 10 children, clinician I opined retinopathy and clinician II was not for retinopathy. For 12 children, clinician II was for retinopathy and clinician I was not for retinopathy.
a. What are we dealing with?
b. What is the crude agreement?
c. What is the chance agreement expected?
d. What is the actual agreement beyond chance?
e. What is the potential agreement beyond chance?
f. What is the final parameter you arrive?
Answer
| a. | Clinical agreement (Kappa coefficient) |
| b. | Crude agreement (Po)  |
46 + 10 + 12 + 32 = 100
| c. | Total chance agreement expected (Pe) |
| = Chance agreement for cell “a” + Chance agreement for cell “d” = 51% | |
| [Chance agreement expected for cell “a” = [(46 + 10) (46 + 12)]/(46 + 10 + 12 + 32) = 56 × 58/100 + Chance agreement expected for cell “d” = [(12 + 32) (10 + 32)]/(46 + 10 + 12 + 32) = 44 × 42/100] | |
| d. | Actual agreement beyond chance = 27 |
| e. | Potential agreement beyond chance = 49 |
| f. | Kappa coefficient = 27 × 100/49 = 55 |
THG37-008
Q37.8
a. What does above image show?
b. What is the purpose of it?
c. What is shown in the “X”-axis?
d. What is shown in the “Y”-axis?
e. What do the solid and dotted lines represent?
Answer
| a. | Bland–Altman plot |
| b. | To evaluate the agreement among two different instruments or two measurements/techniques |
| c. | Mean of two measures |
| d. | Difference between two measures |
| e. | Mean and zero lines |
THG37-009
Fill in with appropriate tools used to critically appraise various types of studies published in a journal.
| Nature of studies | Tools used |
|---|---|
| Systematic reviews and meta-analysis | |
| Meta-analysis of non-RCTs | |
| Randomized controlled trials (RCTs) | |
| Observational studies | |
| Studies on diagnostic test evaluation |
Answer
Tools used to assess various types of studies published in a journal
| Nature of studies | Tools used | | |
| Systematic reviews and meta-analysis | | | |
| • | PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) | |
| • | QUORUM (Quality of Reporting of Meta-Analyses) | |
| • | AMSTAR (Assessment of Multiple Systematic Reviews) | |
| • | CASP (Critical Appraisal Skills Program) check list | |
| | | |
| Meta-analysis of non-RCTs | MOOSE (Meta-Analysis of Observational Studies in Epidemiology) | | |
| Randomized controlled trials | CONSORT (Consolidated Standards of Reporting Trials) | | |
| Observational studies | STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) | | |
| Studies on diagnostic test evaluation | STARD (Standards for Reporting of Diagnostic Accuracy Studies) | | |
THG37-010
Q37.10
a. What do the images A and B show?
b. What is the purpose of this?
c. What do the colors green, yellow, and red represent?
d. What do the signs “+”, “?”, and “-” in image B represent?
e. What are the aspects considered for assessing?
Answer
| a. | Cochrane risk of bias assessment tool (image A)—risk of bias graph; Image B—risk of bias summary |
| b. | Image A: Assesses risk of bias in single study |
| Image B: Summarizes the risk of bias in multiple studies | |
| c. | Green: Low risk of bias; Yellow: Unclear risk of bias; and Red: High risk of bias. |
| d. | “+”: Low risk of bias; “?”: Unclear risk of bias; and “-”: high risk of bias |
| e. | Randomization, allocation concealment, blinding, data on outcome, and incomplete reporting |
THG37-011
Q37.11
a. What does above image deal with?
b. Where is this used?
c. What do the Y/PY, N/PY, and NI represent?
d. What do the questions 1, 2, and 3 represent?
e. What do the “low risk”, “some concerns”, and “high risk” represent?
Answer
| a. | Algorithm for risk of bias in selection of the reported result. This is only a suggested decision tree. |
| b. | This is the algorithm used while assessing the bias in studies included in systematic reviews using revised Cochrane risk of bias assessment tool. |
| c. | Y/PY = “Yes” or “Probably yes”; N/PN = “No” or “Probably no”; NI = “No information” |
| d. | Represent “signaling questions” framed for the “Domain” of “reported result” |
| e. | Judgment of bias in the study |
THG37-012
Q37.12
a. What does below image show?
b. What do the symmetric and asymmetric plots indicate?
c. What do the dots represent?
d. What does the empty left lower corner indicate?
e. What does the empty right lower corner indicate?
Answer
| a. | Funnel plot |
| b. | If the plot is symmetric, no publication bias and if asymmetric, meta-analysis may have missed some trials—usually smaller studies showing no effect. |
| c. | Results of studies included in the analysis |
| d. | Usually smaller studies showing no effect not included in meta-analysis |
| e. | Small studies with larger effect size not included in meta-analysis |
THG37-013
Table showing types of variables—fill in the blanks as applicable
| Quantitative (numerical) uncategorized metric data | ||
| Continuous | 0 | …………………… |
| e.g.,…………………… | e.g., Number of children, number of attacks of asthma per week | |
| …………………… | ||
| …………………… | Ordinal (ordered categories) | Nominal (unordered categories) |
| e.g., Yes/No; present/absent | e.g., Grade of breast cancer; better, same, and worse; disagree, neutral, and agree | e.g.,…………………… |
Answer
Table showing types variables
| Quantitative (numerical)/uncategorized metric data | ||
| Continuous | 0 | Discrete |
| e.g., Blood pressure, height, weight, and age | e.g., Number of children, number of attacks of asthma per week | |
| Qualitative (categorical) | ||
| Categorized metric data | Ordinal (ordered categories) | Nominal (unordered categories) |
| e.g., Yes/No; present/absent | e.g., Grade of breast cancer; better, same, and worse; disagree, neutral, and agree | e.g., Sex (male/female), alive or dead, blood group O, A, B, and AB |
THG37-014
Q37.14
a. What does above image show?
b. For what type of data it is used?
c. What visual impression it captures?
d. What does the line in the box represent?
e. What do the lines at the ends of box represent?
Answer
| a. | Box-and-whiskers plot |
| b. | For data of non-Gaussian distribution |
| c. | Captures variation and skewness visually |
| d. | Median |
| e. | Minimum and maximum values |
THG37-015
In a study to find out the risk of hypertension among those consume high salt, total study subjects recruited were 966. Among them, 414 had the habit of consuming high salt, out of whom 34 were hypertensives. There were 904 normotensives. Among those taking normal salt intake, 28 had hypertension.
a. Attributable risk (AR)?
b. Attributable risk fraction (AR%)?
c. Population attributable risk (PAR)?
d. Population attributable risk fraction (PAR%?)
Answer
| Parameter | | | | | Formula | 0 | Value |
| a. | Attributable risk (AR) | | | | le - lu | 8.21 - 5.07 | 3.14/100 |
| b. | Attributable risk fraction (AR%) | | | | le - lu (AR)/Ie x 100 | 3.14/8.21 x 100 | 38% |
| c. | Population attributable risk (PAR) | | | | Ip - lu | 6.41 - 5.07 | 1.34/100 |
| d. | Population attributable risk fraction (PAR%) | | | | Ip - lu (PAR)/Ip x 100 | 1.34/6.41 x 100 | 21% |
| e. | i. Relative risk (RR) | | | | Outcome among exposed/outcome among unexposed | 34/414 - 28/552 0.08 - 0.05 | 1.6 |
| | | | | | Odds of exposure with outcome/odds of exposure without outcome | 34/28 - 380/524 34 x 524 - 28 x 380 17,816 - 10,640 | 1.6 |
| | ii. | Odds ratio (OR) | |
| | | | |
| (Ie: incidence in exposed, Ip: incidence in entire population, lu: incidence in unexposed) | | | | | | | |
THG37-016
Q37.16
a. What does above image show?
b. What does the step like drop represent?
c. What does the length of the vertical line represent?
d. What does the vertical line mean?
e. What do the “dots” over the lines indicated by arrows denote?
Answer
| a. | Survival analysis curve–Kaplan–Meier curve |
| b. | Drop in the curve occur only at the time of event of interest |
| c. | Represents the change in cumulative probability |
| d. | Vertical lines are just for cosmetic purpose—make curve more pleasing to observe |
| e. | “Dots” over the line indicate censored subjects |
THG37-017
In a study, it was found that mean [standard deviation (SD)] blood sugar of 250 children was 94.0 (3.0).
a. What is the standard error (SE) of mean?
b. What is the 95% confidence interval?
Answer
| a. | SE of mean = SD/√(n) |
| SE of mean = 3.0/250 = 0.19 |
| b. |  |
| 95% CI [(94.0 – 2(0.19), 94.0 + 2(0.19)] | |
| Or | |
| [93.6, 94.4] |
THG37-018
For a study to find out the prevalence of attention deficit hyperactivity disorder (ADHD) among <16 years old children in Chennai, with a predicted prevalence of 4.1% ADHD from previous Delhi study, for a 95% confidence level and for ±1% of actual prevalence (degree of precision).
a. What is the sample size estimated?
Answer
| a. | Formula: |
 |
| Here, | |
| za/2 = 1.96 (for 95% confidence) | |
| p = 0.041 (for 4.1% prevalence) | |
| d = 0.01 (estimate ± 1%) |
= 1.962 × 0.041 × (1 – 041)/0.01
= 3.8416 × 0.039319/0.0001
= 1510.5
THG37-019
It was planned to study the effectiveness of oral iron therapy in anemic children (Hb <10 g/dL) aged 1–5 years. One group was exposed to oral iron with diet and the other group with placebo and diet. A similar study reported improvement of 95% among iron group and 75% among placebo group. For an expected 95% confidence limits and precision of 5%.
a. What is the sample size required in each group?
Answer
| a. | ![The image presents the statistical formula used to calculate sample size when comparing two population proportions. The formula is expressed as (Zα/2)² × [p1(1 − p1) + p2(1 − p2)] divided by d². In this expression, Zα/2 represents the standard normal value corresponding to the desired confidence level, which is 1.96 for a 95% confidence interval. The variables p1 and p2 indicate the anticipated proportions in the two populations being compared. The term d represents the absolute precision required on either side of the difference in proportions, shown as 0.05 or 5%. This formula helps determine the minimum number of participants needed to reliably detect a difference between two proportions in research studies.](image_rsrc1ZU2.jpg) |
| Here, | |
| za/2 = 1.96 (for 95% confidence) | |
| p1, p2 = anticipated value of the proportions in the two populations (75 and 95%) | |
| d = absolute precision required on either side the difference in proportions (5%) |
= 1.962 × 0.75 [(1 – 0.75) + 0.95 (1.0.05)]/0.052
= 3.8416 × [0.1875 + 0.0475]/0.0025
= 3.8416 × 0.90278/0.0025
= 36.1 = 36 in each group
THG37-020
In a study to assess the role of head nodding in predicting hypoxia, 112 children were assessed. Among 57 children who had hypoxia, 29 had head nodding. Two out of 55 who did not have hypoxia presented with head nodding.
a. Sensitivity
b. Specificity
c. Positive predictive value
d. Negative predictive value
Answer
| Head nodding | Hypoxia +ve | Hypoxia -ve | Total |
|---|---|---|---|
| Present | 29 | 2 | 31 |
| Absent | 28 | 53 | 81 |
| Total | 57 | 55 | 112 |
| Parameter | Formula | Exercise | Answer | |
|---|---|---|---|---|
| a. | Sensitivity | Test (head nodding) +ves among total diseased [(hypoxia) (gold standard + ves)] | 29/57 | 50.9% |
| b. | Specificity | Test (head nodding) -ves among total nondiseased [(no hypoxia) (gold standard -ves] | 53/55 | 96.4% |
| c. | Positive predictive value | Diseased [(hypoxia +ve) (gold standard +ves)] among total test (head nodding) +ves | 29/31 | 93.5% |
| d. | Negative predictive value | Nondiseased [(hypoxia -ve) (gold standard -ves)] among total test (head nodding) -ves | 53/81 | 65.4% |
| e. | i. Likelihood ratio for positive test |  |
 |
14.1 |
| ii. Likelihood ratio for negative test |  |
  |
0.5 | |
 |
 |
THG37-021
Q37.21
a. What does below image show?
b. What do the names and numbers in the first column represent?
c. What do the numbers in the rest of the columns on left hand side represent?
d. What do the numbers on the right hand represent?
e. What does the vertical line represent?
Answer
| a. | Forest plot |
| b. | First column on left-hand lists the names of the studies (usually RCTs or epidemiological studies), commonly in chronological order from the top downward |
| c. | These columns represent number of study subjects with and without outcome among intervened and unintervened (exposed and unexposed) in causal association studies |
| d. | Right-hand column is a plot of the measure of effect (e.g., an odds ratio) for each of these studies (often represented by a square) with confidence intervals. |
| e. | “Line of null effect” |
THG37-022
Identify correct responses with reference to significance for the odds ratio and 95% confidence intervals mentioned.
| OR (95% CI) | Significance |
|---|---|
| 9 (0.6-12.0) | Significant/Not significant |
| 9 (9.5-12.0) | Significant/Not significant |
| 9 (6.0-102.0) | Significant/Not significant |
| 9 (5.00-12.0) | Significant/Not significant |
Answer
| OR (95% CI) | Significance |
|---|---|
| 9 (0.6-12.0) | Not significant |
| 9 (9.5-12.0) | Not significant |
| 9 (6.0-102.0) | Not significant |
| 9 (5.00-12.0) | Significant |
THG37-023
Match the terms with appropriate explanations.
| Terms | | | Explanation | | |
| | | | | | |
| 1. | Population | | 1. | Measures obtained for entire target population | |
| | | | | | |
| | | | | | |
| 2. | Parameter | | 2. | Fraction of the population that is selected. | |
| | | | | | |
| | | | | | |
| 3. | Variability in sources | | 3. | Target group of investigation | |
| | | | | | |
| | | | | | |
| 4. | Sample | | 4. | Measures obtained for sample population | |
| | | | | | |
| | | | | | |
| 5. | Statistic | | 5. | Uncertainties in Medical Care | |
| | | | | | |
Answer
Explanations for various terms
| Term | | | Explanation | | |
| | | | | | |
| 1. | Population | | 3. | Target group of investigation | |
| | | | | | |
| | | | | | |
| 2. | Parameter | | 1. | Measures obtained for entire target population | |
| | | | | | |
| | | | | | |
| 3. | Variability in sources | | 5. | Uncertainties in medical care | |
| | | | | | |
| | | | | | |
| 4. | Sample | | 2. | Fraction of the population that is selected | |
| | | | | | |
| | | | | | |
| 5. | Statistic | | 4. | Measures obtained for sample population | |
| | | | | | |
THG37-024
Match the terms with appropriate explanations.
| Terms | | | Explanation | | |
| | | | | | |
| 1. | Null hypothesis (H0) | | 1. | A specific direction is predicted | |
| | | | | | |
| | | | | | |
| 2. | Two-tailed hypothesis | | 2. | There is a relationship | |
| | | | | | |
| | | | | | |
| 3. | Alternate hypothesis (HA) | | 3. | No relationship | |
| | | | | | |
| | | | | | |
| 4. | One-tailed hypothesis | | 4. | Specific statement of prediction | |
| | | | | | |
| | | | | | |
| 5. | Hypothesis | | 5. | No direction is predicted | |
| | | | | | |
Answer
Explanations for various terms
| Term | | | Explanation | | |
| | | | | | |
| 1. | Null hypothesis (H0) | | 3. | No relationship | |
| | | | | | |
| | | | | | |
| 2. | Two-tailed hypothesis | | 5. | No direction is predicted | |
| | | | | | |
| | | | | | |
| 3. | Alternate hypothesis (HA) | | 2. | There is a relationship. | |
| | | | | | |
| | | | | | |
| 4. | One-tailed hypothesis | | 1. | A specific direction is predicted. | |
| | | | | | |
| | | | | | |
| 5. | Hypothesis | | 4. | Specific statement of prediction | |
| | | | | | |
THG37-025
Match the appropriate “tests of significance” for the scenario mentioned.
| Scenario | | | Statistical test preferred | | |
| | | | | | |
| 1. | Comparison of two groups means independent | | 1. | Wilcoxon rank-sum (Mann-Whitney U test) | |
| | | | | | |
| | | | | | |
| 2. | Comparison of two groups means of non-Gaussian distribution | | 2. | Student’s t-test (unpaired) | |
| | | | | | |
| | | | | | |
| 3. | Comparison of means in >3 groups | | 3. | Student’s i-test (paired) | |
| | | | | | |
| | | | | | |
| 4. | Comparison of paired mean values | | 4. | Wilcoxon signed-rank test | |
| | | | | | |
| | | | | | |
| 5. | Comparison of paired values of non-Gaussian distribution | | 5. | Analysis of variance (ANOVA) | |
| | | | | | |
Answer
Tests of significance preferred for various questions
| Scenario | | | Statistical test preferred | | |
| | | | | | |
| 1. | Comparison of two groups means independent | | 2. | Student’s t-test (unpaired) | |
| | | | | | |
| | | | | | |
| 2. | Comparison of two groups means of non-Gaussian distribution | | 1. | Wilcoxon rank-sum (Mann-Whitney U test) | |
| | | | | | |
| | | | | | |
| 3. | Comparison of means in >3 groups | | 5. | Analysis of variance (ANOVA) | |
| | | | | | |
| | | | | | |
| 4. | Comparison of paired mean values | | 3. | Student’s f-test (paired) | |
| | | | | | |
| | | | | | |
| 5. | Comparison of paired values of non-Gaussian distribution | | 4. | Wilcoxon signed-rank test | |
| | | | | | |
THG37-026
Match the statements in the columns with reference to the “levels of evidence” appropriately.
| Level of evidence | | | Explanation | | |
| | | | | | |
| 1. | Level I | | 1. | Strong evidence from at least one properly designed RCT of appropriate size | |
| | | | | | |
| | | | | | |
| 2. | Level II | | 2. | Evidence from well-designed nonexperimental studies from more than one center or research group | |
| | | | | | |
| | | | | | |
| 3. | Level III | | 3. | Strong evidence from at least one systematic review of multiple well-designed RCTs | |
| | | | | | |
| | | | | | |
| 4. | Level IV | | 4. | Opinion of research authorities, based on clinical evidence, descriptive studies, or report from expert groups | |
| | | | | | |
| | | | | | |
| 5. | Level V | | 5. | Evidence from well-designed trials, such as nonrandomized trials, cohort studies, timed series, or matched case-control studies | |
| | | | | | |
Answer
Levels of evidence
| Level of evidence | | | Explanation | | |
| | | | | | |
| 1. | Level I | | 3. | Strong evidence from at least one systematic review of multiple well-designed RCTs | |
| | | | | | |
| | | | | | |
| 2. | Level II | | 1. | Strong evidence from at least one properly designed RCT of appropriate size | |
| | | | | | |
| | | | | | |
| 3. | Level III | | 5. | Evidence from well-designed trials such as nonrandomized trials, cohort studies, timed series or matched case-control studies | |
| | | | | | |
| | | | | | |
| 4. | Level IV | | 2. | Evidence from well-designed nonexperimental studies from more than one center or research group | |
| | | | | | |
| | | | | | |
| 5. | Level V | | 4. | Opinion of research authorities, based on clinical evidence, descriptive studies, or report from expert groups | |
| | | | | | |
THG37-027
Mention against each statement regarding the “Institutional Ethics Committee (IEC)” whether it is True or False.
| Statement | | | True/False | | |
| | | | | | |
| 1. | IEC is dependent on other committees and the needs of the institution | | 1. | True/False | |
| | | | | | |
| | | | | | |
| 2. | All research involving human subjects (or their records) must be reviewed by an Institutional Review Board (IRB) | | 2. | True/False | |
| | | | | | |
| | | | | | |
| 3. | IEC cannot take up the responsibility of review of both the scientific content and ethical aspects of the proposal | | 3. | True/False | |
| | | | | | |
| | | | | | |
| 4. | One institution cannot have more than one IRB | | 4. | True/False | |
| | | | | | |
| | | | | | |
| 5. | Small institutions could form alliance with other IECs or approach registered IEC | | 5. | True/False | |
| | | | | | |
Answer
| Statement | | | True/False | | |
| | | | | | |
| 1. | IEC is dependent on other committees and the needs of the institution | | 1. | False | |
| | | | | | |
| | | | | | |
| 2. | All research involving human subjects (or their records) must be reviewed by an IRB | | 2. | True | |
| | | | | | |
| | | | | | |
| 3. | IEC cannot take up the responsibility of review of both the scientific content and ethical aspects of the proposal | | 3. | False | |
| | | | | | |
| | | | | | |
| 4. | One institution cannot have more than one IRB | | 4. | False | |
| | | | | | |
| | | | | | |
| 5. | Small institutions could form alliance with other IECs or approach registered IEC | | 5. | True | |
| | | | | | |
Note: When we have justified that including OSCEs is possible in various aspects under Research Methods and Biostatistics, it should be realized that there are many more aspects which can be formulated in different other forms, even in more novel presentations. The issues covered are only representative samples from Research Methods and Biostatistics, which is true with reference to other subjects as well.