OFFICIAL STATISTICS SPECIALLY DESIGNED FOR INDIAN STATISTICAL SERVICE (ISS) AND OTHER GOVERNMENT & PRIVATE SECTOR STATISTICAL EXAMINATIONS
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Where do India's official birth rate, death rate, infant mortality rate and total fertility rate come from? Mostly from the Sample Registration System (SRS), a large demographic sample survey run by the Registrar General of India. It is a classic Official Statistics topic in Indian Statistical Service (ISS) papers because it combines survey design with a neat estimation idea, and it also appears in RBI, NABARD, SSC and university statistics exams. This guide gives you the design, the estimator and three exam-style questions.
1. What is the Sample Registration System?
SRS is a continuous demographic survey that gives reliable annual estimates of fertility and mortality at the national and state level. It began on a pilot basis in the mid-1960s and became a full-fledged system from 1969-70. It is run by the Office of the Registrar General and Census Commissioner, Ministry of Home Affairs.
Why examiners love this topic
Civil registration is still incomplete in parts of the country, so a sample system is needed to get true vital rates. The dual record system and the capture-recapture logic behind it make an ideal numerical question.
2. How does the dual record system work?
In each sample unit (a village or an urban block), two independent sources record every birth and death. The two lists are then matched.
Continuous enumeration
A resident part-time enumerator, such as a teacher or anganwadi worker, records births and deaths as they occur.
Half-yearly survey
An independent, full-time supervisor carries out a retrospective survey every six months, without seeing the enumerator's records.
Matching
The two lists are matched. Unmatched and partially matched events are re-verified in the field to fix the final count.
Exam tip
SRS is not the same as the Civil Registration System (CRS). CRS depends on people registering events, so it can be incomplete. SRS is a sample survey, and it is also used to judge how complete registration is.
3. The estimation formula
Matching tells us how many events each system missed. The Chandra Sekar-Deming (capture-recapture) estimator uses this to estimate the true number of events.
Here n1 and n2 are the events recorded by the two systems, m is the number matched, and u1, u2 are the unmatched events in each system. The term u1u2/m estimates the events missed by both.
- Assumption: the two systems work independently of each other.
- Assumption: every event has the same chance of being captured, and matching is error-free.
- Bias: if the systems are positively dependent, the estimate falls short of the true number.
4. Vital rates from SRS at a glance
| Indicator | Formula |
|---|---|
| Crude birth rate (CBR) | ( Live births / Mid-year population ) × 1,000 |
| Crude death rate (CDR) | ( Deaths / Mid-year population ) × 1,000 |
| Infant mortality rate (IMR) | ( Deaths under 1 year / Live births ) × 1,000 |
| Total fertility rate (TFR) | 5 × Σ age-specific fertility rates (five-year age groups) |
| Sex ratio at birth | Female births per 1,000 male births |
SRS reports give the latest values. Check the most recent SRS report before quoting numbers.
5. CRS vs SRS vs Census: the comparison that keeps coming up
| Basis | Civil Registration System | Sample Registration System | Population Census |
|---|---|---|---|
| Method | Legal registration of each event | Dual record sample survey | Complete enumeration |
| Coverage | All events, but reporting can be incomplete | Sample units across states | Whole population |
| Frequency | Continuous | Annual estimates | Every 10 years |
| Main use | Legal and administrative records | Vital rates at national and state level | Population size and structure |
6. Common mistakes students make
- Treating the dual record system as double counting. Matching removes duplicates.
- Attributing SRS to NSO. SRS is run by the Registrar General of India.
- Quoting IMR per 1,000 population. It is per 1,000 live births.
- Forgetting the factor 5 in TFR when using five-year age groups.
- Assuming CRS gives complete vital rates in every state. Registration completeness varies.
7. Three important questions on SRS
Try each one on your own first, then tap the answer.
What is the dual record system in SRS, and why is it used?
Show answer
Two independent systems record the same births and deaths: continuous enumeration by a resident enumerator and a half-yearly retrospective survey by a supervisor. The lists are matched, and the unmatched events show how many each system missed. It is used to correct under-reporting and to estimate events missed by both systems.
In a sample, continuous enumeration recorded 480 births and the half-yearly survey recorded 450 births. 420 births were common to both. Estimate the true number of births by the Chandra Sekar-Deming method, the coverage of each system, and the crude birth rate if the mid-year population is 20,000.
Show answer
Estimated births = 480 × 450 / 420 = 216,000 / 420 = 514.3, about 514.
Coverage of continuous enumeration = 420 / 450 = 93.3%. Coverage of the half-yearly survey = 420 / 480 = 87.5%.
CBR = 514.3 / 20,000 × 1,000 = 25.7 per 1,000.
Describe the Sample Registration System in India. Discuss its design, estimation method and limitations.
Show answer
Write your answer in four parts. (a) Purpose and organisation: SRS gives annual fertility and mortality estimates at national and state level and is run by the Registrar General of India. (b) Design: a sample of villages and urban blocks in each state; in each unit, a resident enumerator records events continuously and a supervisor independently surveys every six months. (c) Estimation: the two lists are matched, mismatches are verified in the field, and the Chandra Sekar-Deming estimator corrects for events missed by both; rates such as CBR, CDR, IMR and TFR are then computed. (d) Limitations: the independence assumption may not hold, sample size limits estimates for small areas, matching and recall errors are possible, and results appear with a time lag. Conclude that SRS remains the main source of vital rates until civil registration is fully complete.
Key takeaways
- SRS is run by the Registrar General of India and uses a dual record system.
- The Chandra Sekar-Deming estimator is n1n2/m, a capture-recapture idea.
- IMR is per 1,000 live births, and TFR needs the factor 5 with five-year age groups.
- SRS complements CRS, which can be incomplete, and the decennial Census.
Everything on Official Statistics, in one book
SRS is just one chapter of the syllabus. If you want the complete picture, this book is built for you.
- Indian official statistical system: MoSPI, NSO, NSC and the data they produce
- National accounts, GDP, IIP, price indices and labour statistics
- NSS surveys, sampling designs and data quality concepts
- Written specially for the ISS exam, and useful for other government and private sector statistical exams
- Concept-focused notes to revise quickly before the exam
Official Statistics for ISS and other Government & Private Sector Statistical Examinations