In the “De facto” method of census data collection, information is collected based on which of the following?

Explanation

## Correct Answer: B. Location at the time of enumeration The "de facto" method of census enumeration is defined by the **location of the person at the time of the census enumeration**, not their permanent residence or other demographic attributes. This is a fundamental principle in population statistics and census methodology as outlined in Park's Textbook of Preventive and Social Medicine. In India's Census operations (conducted by the Office of the Registrar General), the de facto method counts individuals based on where they physically are on the census night/day. This contrasts with the "de jure" method, which counts people based on their usual place of residence regardless of where they happen to be on census day. The de facto approach is particularly useful in countries like India where internal migration, seasonal movement, and temporary displacement are common. It provides a snapshot of the actual population distribution at a specific moment, which is critical for resource allocation, infrastructure planning, and understanding real-time population density in urban and rural areas. The de facto method was used in India's 2011 Census and remains the standard approach for most national censuses worldwide. ## Why the other options are wrong **A. Place of birth** — Place of birth is a demographic characteristic recorded in census data but is NOT the defining criterion for the de facto method. Birth place remains constant throughout life and is irrelevant to enumeration methodology. This option confuses a census variable with the enumeration principle itself—a common NBE trap. **C. Place of employment** — While place of employment may be recorded as census data, it is not the basis for de facto enumeration. A person may be employed in one location but enumerated elsewhere (e.g., working in Delhi but sleeping in a satellite town). This conflates occupational data collection with the fundamental enumeration method. **D. Usual place of residence** — This is the defining criterion for the **de jure** method, not de facto. Students often confuse these two approaches. De jure counts people at their usual residence; de facto counts them where they physically are on census day. This is the classic NBE trap in this question. ## High-Yield Facts - **De facto method** = enumeration based on location at the time of census (physical presence on census night/day). - **De jure method** = enumeration based on usual place of residence, regardless of physical location on census day. - India's Census (2011 onwards) primarily uses the **de facto approach** for population enumeration. - De facto is preferred in high-migration countries like India because it reflects actual population distribution for resource planning. - **Key difference**: De facto captures transient populations (migrants, homeless, travelers); de jure may miss them if they're away from usual residence. ## Mnemonics **De Facto = FACT-o (Fact = where you ARE)** De **Facto** → **Fact** of the moment → where you ARE on census day. De **Jure** → **Jurisdiction** of residence → where you LIVE usually. **Location vs. Residence** **De Facto** = Location (where you sleep on census night). **De Jure** = Usual Residence (where you normally live). Remember: Facto = Fact = Physical presence. ## NBE Trap NBE pairs "usual place of residence" (de jure) with census enumeration to trap students who confuse the two methods. The question tests whether students understand the *defining criterion* of de facto (physical location at enumeration) versus de jure (permanent/usual residence). ## Clinical Pearl In India's urban slums and migrant worker populations, de facto enumeration captures the actual number of people needing healthcare, water, and sanitation services on a given day—critical for public health planning. De jure would undercount these transient populations, leading to inadequate resource allocation in high-migration areas. _Reference: Park's Textbook of Preventive and Social Medicine, Ch. 3 (Census and Vital Statistics)_