INI-CET 2026 - Community Medicine PYQs Practice Questions

Q: Calculate the Odds Ratio with the following data: Cancer No Cancer Smoking 80 20 No Smoking 40 60

6. ***6*** - The **Odds Ratio (OR)** is calculated using the formula: (a * d) / (b * c), where (a) is exposed with disease, (b) is exposed without disease, (c) is unexposed with disease, and (d) is unexposed without disease. - Plugging in the values: (80 * 60) / (20 * 40) = 4800 / 800 = **6**, which represents the odds of developing **cancer** among smokers compared to non-smokers. *8* - This result would be obtained if the calculation was incorrect or if the **cross-multiplication** was mismatched during the division step. - It does not represent the correct mathematical ratio of the **exposure-disease association** provided in the table. *10* - This value likely arises from a calculation error, perhaps by substituting one of the denominators or numerators incorrectly, such as summing **incorrect cells**. - In **biostatistics**, ensuring the accurate placement of data in the **2x2 contingency table** is critical for deriving the correct odds. *12* - This result is mathematically incorrect and suggests a failure to properly apply the **odds ratio formula** to the provided contingency table data. - An OR of 12 would imply a much stronger **association** than what is actually supported by the raw frequencies of smoking and cancer incidence in this study group. [Practice more Community Medicine PYQs on OnCourse]

Q: Health data from 15 nations investigates the relationship between per capita tobacco consumption and national COPD prevalence, revealing a strong positive correlation. Which study type best describes this?

Ecological study. ***Ecological study*** - An ecological study assesses the relationship between exposure and outcome at the **population level** rather than the individual level, using data aggregated across nations as in this example. - The unit of analysis is the **entire population** (15 nations), making it the correct classification for this type of correlational research. *Case control study* - Requires individual-level data by identifying subjects based on the presence or absence of the **outcome** (COPD) and looking back for the **exposure** (tobacco). - It is not used to analyze aggregate national-level data like per capita consumption metrics. *Cohort study* - Involves following a group of individuals over time to determine if exposure leads to the subsequent development of the outcome. - Because this study assesses prevalence and consumption across nations simultaneously at the population level, it does not involve the prospective follow-up characteristic of a cohort study. *Cross sectional study* - Analyzes individual-level data to capture a snapshot of exposure and disease at a single point in time. - Because this study uses group-level (nations) data rather than individual subject data, it is specifically referred to as an ecological study, not a cross-sectional study. [Practice more Community Medicine PYQs on OnCourse]

Q: A new screening test is evaluated in a population of 1,000 individuals. Of these, 100 individuals are known to have the disease. The test correctly identifies 90 of the diseased individuals, while 50 non-diseased individuals are false positive. Based on the data below, what is the Positive Predictive Value (PPV) of this screening test? Screening Test Diseased Non-Diseased Test Positive 90 50 Test Negative 10 850 Total 100 900

64%. ***64%*** - The **Positive Predictive Value (PPV)** is calculated by the formula: **True Positives / (True Positives + False Positives)**. - Plugging in the values from the table: **90 / (90 + 50) = 90 / 140 ≈ 0.643**, which is approximately **64%**. *90%* - This represents the **Sensitivity** of the test, calculated as **True Positives / (True Positives + False Negatives)** (90 / 100). - It measures the ability of a test to correctly identify individuals who actually have the disease. *98%* - This calculation is incorrect and does not correspond to standard diagnostic test parameters. - A value this high would imply nearly perfect predictive capability, which is not supported by the data provided. *47%* - This value is likely obtained by calculating the **Negative Predictive Value (NPV)** incorrectly or using the wrong denominator. - It does not represent the probability that a person with a positive test result truly has the disease. [Practice more Community Medicine PYQs on OnCourse]

Q: In a defined population, approximately 67% of all stroke cases are attributable to uncontrolled hypertension. If hypertension were adequately managed, 2/3rd of stroke burden could be eliminated. This is an example of:

Population attributable risk. ***Population attributable risk*** - This measure represents the **proportion of disease in the total population** that can be attributed to a specific exposure, which is directly applicable to the scenario where 67% of stroke cases are linked to hypertension. - It estimates the **potential impact** of a public health intervention, such as eliminating hypertension, on the total disease burden in the population. *Relative risk* - This is a ratio of the **incidence in the exposed group** compared to the incidence in the unexposed group. - It measures the **strength of the association** between a risk factor and an outcome, rather than the proportion of the disease attributable to the risk factor. *Attributable risk* - Often called **Risk Difference**, this measure calculates the actual difference in incidence rates between exposed and unexposed groups. - It does not account for the **prevalence of the exposure** in the entire population, unlike population attributable risk which considers the total disease burden. *Odds Ratio* - This statistical measure determines the odds of an exposure occurring in cases compared to the odds of exposure in controls, commonly used in **case-control studies**. - It is an estimate of relative risk (when disease is rare) but does not quantify the **portion of population disease** caused by the risk factor. [Practice more Community Medicine PYQs on OnCourse]

Question 1

Calculate the Odds Ratio with the following data:

Cancer No Cancer
Smoking 80 20
No Smoking 40 60

Accepted Answer

6

Answer

8

Answer

10

Answer

12

Question 2

Assertion: In a nested case-control study, incidence rates can be derived from the parent cohort.
Reason: Nested case-control studies have the ability to estimate relative risk accurately.

Accepted Answer

Both assertion and reason are correct, but they are unrelated

Answer

Both assertion and reason are correct, and the reason is the correct explanation of the assertion

Answer

Assertion is correct, but the reason is incorrect

Answer

Assertion is incorrect, but the reason is correct

Question 3

Health data from 15 nations investigates the relationship between per capita tobacco
consumption and national COPD prevalence, revealing a strong positive correlation. Which study
type best describes this?

Accepted Answer

Ecological study

Answer

Case control study

Answer

Cohort study

Answer

Cross sectional study

Question 4

A new screening test is evaluated in a population of 1,000 individuals. Of these, 100 individuals
are known to have the disease. The test correctly identifies 90 of the diseased individuals, while 50
non-diseased individuals are false positive. Based on the data below, what is the Positive
Predictive Value (PPV) of this screening test?
Screening Test Diseased Non-Diseased
Test Positive 90 50
Test Negative 10 850
Total 100 900

Accepted Answer

64%

Answer

90%

Answer

98%

Answer

47%

Question 5

In a defined population, approximately 67% of all stroke cases are attributable to uncontrolled
hypertension. If hypertension were adequately managed, 2/3rd of stroke burden could be
eliminated. This is an example of:

Accepted Answer

Population attributable risk

Answer

Relative risk

Answer

Attributable risk

Answer

Odds Ratio

Question 6

Which statement is correct regarding assessment of heterogeneity in meta-analysis?

Accepted Answer

It evaluates the degree of variability in results across the combined studies

Answer

It directly quantifies and corrects for publication bias

Answer

It automatically removes confounding variables from individual studies

Answer

It computes the incidence rate of the outcome across all populations

Question 7

On investigating an outbreak, an epidemiologist plots epidemic curve of acute febrile illness
showing successive clusters separated by approximately 1 incubation period apart. Which of the
following diseases shows this pattern of propagated spread?

Accepted Answer

Measles

Answer

Salmonellosis

Answer

Typhoid

Answer

Food poisoning

Question 8

On evaluating an influenza vaccine, it demonstrated an efficacy of 95% in randomized controlled
trials and an effectiveness of 90% in post-marketing surveillance studies. Which of the following
statement is incorrect?

Accepted Answer

The vaccine confers absolute and complete protection against influenza infection

Answer

Vaccinated individuals demonstrate a 95% reduction in disease risk vs unvaccinated

Answer

Vaccinated individuals show a 90% reduction in influenza risk in real-world settings

Answer

Vaccine effectiveness can be lower than efficacy in real-world settings

Question 9

Which of the following statement is correct with respect to the Pearl Index?

Accepted Answer

Number of accidental pregnancies per 100 woman-years of contraceptive use

Answer

Number of accidental pregnancies in 100 women using a contraceptive for 1 year

Answer

Number of live births per 100 woman-years

Answer

Number of pregnancies including abortions per 100 couples

Question 10

Under the RMNCH+A programme, a state is categorized in the "Red" zone. Which criterion is
likely responsible for this classification?

Accepted Answer

IMR exceeding the national average by 20% or more

Answer

MMR lower than the national benchmark

Answer

Institutional delivery rate meeting the nationally accepted threshold

Answer

Full immunization coverage achieving the desired target

INI-CET 2026 — Community Medicine