UGC NTA NET/JRF Exam, Social Medicine & Community Health, June-2025

Total Questions: 100

91. (Qs. No. 91-95): Read the following passage and answer the question:

A colon cancer study is being conducted in city X to assess the performance of Hemoccult-I as a screening test. Individuals more than 50 years old were screened with Hemoccult-I test, in which a stool sample was tested for presence of blood.

Thereafter, all the individuals were also subjected to colonoscopy and biopsy for the confirmatory diagnosis of colon cancer. The following 2 × 2 table shows the results of the study.

Colon Cancer (+)Colon Cancer (-)Total
Hemoccult-I+ (Positive)4,00019,00023,000
- (Negative)1,00076,00077,000
Total5,00095,000100,000

Which of the following best represents calculation of specificity of Hemoccult-I test?

Correct Answer: 1.
Solution:

Specificity measures the ability of a test to correctly identify those without disease (true negatives).
Specificity

92. Which of the following best represents calculation of sensitivity of Hemoccult-I test?

Correct Answer: 1.
Solution:

Sensitivity measures the ability of a test to correctly identify those with disease (true positives).
Sensitivity

93. Which of the following best represents calculation of Positive Predictive Value (PPV) of Hemoccult-I test?

Correct Answer: 2.
Solution:

Positive Predictive Value (PPV) measures the probability that subject with a positive test actually have the disease.
PPV

94. If the same Hemoccult-I Test is done in another city 'B' having double the prevalence of colon cancer, what will be effect on the Positive Predictive Value (PPV) and Negative Predictive Value (NPV)?

Correct Answer: 3. PPV will increase and NPV will decrease
Solution:

Effect of Increased Prevalence on PPV and NPV: When the prevalence of a disease increases, the number of true positives in the screened population rises.
Let's recall the definitions:
As prevalence increases, there are more true positives (TP) and fewer false positives (FP) relative to total positives-so PPV increases (because a positive test is now more likely to be truly diseased).

However, the number of people with the disease among those testing negative (FN) also increases, reducing NPV.

95. In an alternate hypothetical strategy, another test Hemoccult-II is also introduced as part of screening in city 'X'. Only individuals who test positive on Hemoccult-I, are tested with Hemoccult-II. Only the individuals who test positive on both the tests, are labelled as 'screening positive'. What happens to the Net Sensitivity and Net Specificity for screening?

Correct Answer: 4. Net Sensitivity decreases and Net Specificity increases
Solution:

Effect of Serial Testing (Hemoccult-I + Hemoccult-II)
In this scenario, two tests are applied in series:

  • Only individuals positive on both tests are labelled "screening positives".
  • Those negative on even one test are considered "screeningg negative".

This setup affects test characteristics as follows:

  • Net Senstivity (decreases): Since both tests must be positive, some true disease cases that are positive on the first test but missed by the second are lost-resulting in fewer true positives overall.
  • Net Specificity (increases): Because the chance of false positives on both tests is lower than on either alone, the test combination correctly excludes more diseasefree individuals.

Therefore:

  • Net Sensitivity decreases
  • Net Specificity increases.

96. (Qs. No. 96-100): Read the following passage and answer the question:

The mid-year population of PHC X for the year 2023 was 45,000. The crude birth rate and crude death rate for PHC X of the same year were 20 and 5 per thousand population respectively.

Out of the total children born during the year 2023, 30 died within one year of birth, of which 25 died within first four weeks of age. Of all the infant deaths, 15 died during the first week of life.

There were 6500 women in the reproductive age group in PHC X during the same year. There were 8 maternal deaths during the year.

Which among the following represents post neonatal mortality rate for the PHC X for the year 2023?

Correct Answer: 1.
Solution:

97. Which among the following represents late neonatal mortality rate for the PHC 'X' for the year 2023?

Correct Answer: 1.
Solution:

98. Which among the following is most likely to represent the approximate number of pregnant women in PHC X during the year 2023?

Correct Answer: 4. 990
Solution:

99. Which among the following best represents the denominator in the calculation of maternal mortality rate of PHC X for the year 2023?

Correct Answer: 1. 900
Solution:

100. Which among the following MCH indicators is universally regarded as most important indicator of health status of a community?

Correct Answer: 2. Infant mortality rate
Solution:

Among MCH (Maternal and Child Health) indicators, the Infant Mortality Rate (IMR) is universally accepted as the best single indicator of the overall health status and socio-economic development of a community.