Epidemiology

Chandler’s Index: This is a measure used in parasitology to estimate the intensity of hookworm infection within a community. It represents the average number of hookworm eggs per gram of faeces, providing a quantitative indication of the prevalence and intensity of the infection.

Other options:

• Breteau Index: An entomological index used to measure the density of mosquito larvae.
• House Index: Percentage of houses infested with larvae or pupae of mosquitoes.
• Burrow Index: Not a standard index related to parasitology or entomology.

The correct matches are:

• A. True-positive: Person has disease and screening test result is positive (IV). This indicates the test correctly identifies those with the disease.
• B. True-negative: Person does not have disease and screening test result is negative (II). This indicates the test correctly identifies those without the disease.
• C. False-positive: Person does not have disease and screening test result is positive (I). This occurs when the test wrongly identifies a person as having the disease.
• D. False-negative: Person has disease and screening test result is negative (III). This occurs when the test wrongly identifies a person as disease-free.

Thus, the correct sequence is: (A) - (IV), (B) - (II), (C) - (I), (D) - (III).

The correct matches are:

• A. Case-control study: The outcome is Time, place, and person distribution, focusing on identifying associations in specific settings.
• B. Cohort study: The outcome is Prevalence, assessing the frequency of a condition over a given time.
• C. Cross-sectional study: The outcome is Relative risk, estimating the likelihood of disease presence in relation to exposure.
• D. Descriptive study: The outcome is Odds ratio, measuring associations between risk factors and outcomes descriptively.

Thus, the correct sequence is: (A) - (II), (B) - (IV), (C) - (I), (D) - (III).

Observational studies are those where the researcher does not intervene but simply observes and analyzes data.

• Case-control study: A retrospective study comparing individuals with a specific condition (cases) to those without it (controls).
• Cohort study: A longitudinal study observing a group (cohort) over time to assess the development of outcomes based on exposures.
• Randomised Controlled Trial (RCT): This is an interventional study where participants are randomly assigned to groups.
• Non-randomised Trial: Though it lacks randomization, it involves intervention, making it non-observational.

Thus, the correct answer is (A) and (B) only.

• Oral cancer: Most common in Indian males due to tobacco chewing and smoking.
• Lung cancer: Common globally but second to oral cancer in India.
• Prostate cancer: More common in Western countries.
• Stomach cancer: Less common compared to oral cancer in India.

• Cohort study: Observational, follows groups over time.
• Case-control study: Retrospective comparison of cases and controls.
• Cross-sectional study: Snapshot at a single point in time.
• Randomized Controlled Trial: Experimental study with random allocation.

• Minimizes selection bias
• Allows causal inference
• Provides high-quality evidence