Correct Answer: D. Location at the time of enumeration
The "de facto" method of census data collection is based on location at the time of enumeration — that is, where a person is physically present on the census date, regardless of their usual residence or legal domicile. This is the defining principle of de facto enumeration, as opposed to the "de jure" method which records people at their usual place of residence. In India's decennial census (conducted every 10 years under the Census Act, 1948), the de facto approach counts all persons present in a location on census night, including temporary residents, migrants, and transient populations. This method captures the actual population distribution and is particularly important in India where internal migration, seasonal labour, and temporary settlements are significant. The de facto method provides a snapshot of population density and distribution at a specific moment in time, which is critical for urban planning, resource allocation, and understanding demographic patterns in a country with high population mobility.
Why the other options are wrong
A. Usual place of residence — This is the basis of the de jure method, not de facto. De jure enumeration records people at their permanent or usual place of residence, even if they are temporarily absent on census night. This is the opposite principle from de facto collection and is a common NBE trap for students who confuse the two census methodologies. B. Place of birth — Place of birth is demographic information collected during census enumeration but is not the basis for deciding where to enumerate someone. De facto method does not use birthplace as the enumeration criterion. This is a distractor that conflates census variables with enumeration methodology. C. Place of employment — While place of employment is recorded as census data, it is not the basis for de facto enumeration. A person is enumerated at their location on census night, not necessarily where they work. This option confuses occupational data collection with the enumeration principle itself.
High-Yield Facts
- De facto method = enumeration based on physical location at the time of census night, capturing all persons present regardless of usual residence
- De jure method = enumeration based on usual place of residence, counting people at their permanent home even if temporarily absent
- India's decennial census uses de facto enumeration as the primary method to capture actual population distribution and density
- De facto method is superior for urban planning and resource allocation because it reflects real-time population concentration
- Temporary residents, migrants, and transient populations are included in de facto enumeration but excluded from de jure counts
Mnemonics
De FACTO = FACT-o (where you are FACTUALLY present) De FACTO = where you are FACTUALLY/physically present on census night. De JURE = where you USUALLY/legally belong. Use: When distinguishing enumeration methods in census questions.
NBE Trap
NBE pairs "usual place of residence" (option A) with census methodology to trap students who conflate de facto with de jure enumeration — both are valid census concepts, but only de facto uses location at enumeration time.
Clinical Pearl
In India's decennial census, the de facto method captures floating populations (migrant workers, seasonal labourers, homeless persons) at their actual location on census night, which is why census night enumeration is conducted simultaneously across the country — this ensures accurate representation of India's highly mobile population for health planning and resource distribution.
_Reference: Park's Textbook of Preventive and Social Medicine, Census Methods and Vital Statistics chapter_