Chapter 6 — Vital Statistics
Key Concepts Quick Recap
| Measure | Formula | Unit |
|---|
| Crude Birth Rate (CBR) | (B/P) × 1000 | per 1000 population |
| Crude Death Rate (CDR) | (D/P) × 1000 | per 1000 population |
| Infant Mortality Rate (IMR) | (Deaths under 1 year / Live births) × 1000 | per 1000 live births |
| General Fertility Rate (GFR) | (Live births / Women 15-49) × 1000 | per 1000 women |
| Total Fertility Rate (TFR) | Σ(ASFR) × 5 | children per woman |
| Natural Growth Rate | CBR − CDR | per 1000 population |
I. Choose the Best Answer (MCQs)
1. Crude Birth Rate is expressed as births per: (a) 100 population (b) 1000 population (c) 10,000 population (d) 1 lakh population
Answer(b) 1000 population CBR = (Live births in a year / Mid-year total population) × 1000.
2. Infant Mortality Rate (IMR) measures deaths of children: (a) Under 5 years (b) Under 1 year per 1000 live births (c) Under 2 years (d) All children under 18
Answer(b) Under 1 year per 1000 live births IMR = (Deaths of children under 1 year / Number of live births in that year) × 1000. IMR is a key indicator of health care quality and socioeconomic development.
3. Natural Growth Rate of a population is: (a) CBR + CDR (b) CBR − CDR (c) CBR / CDR (d) (CBR + CDR)/2
Answer(b) CBR − CDR Natural Growth Rate (NGR) = CBR − CDR (per 1000). If CBR > CDR → population growing. If CBR < CDR → population declining. Does not include migration.
4. General Fertility Rate uses as denominator: (a) Total female population (b) Women aged 15-49 (c) Total population (d) Married women only
Answer(b) Women aged 15-49 GFR uses women in the reproductive age group (15-49 years) as denominator → more accurate measure of fertility than CBR.
5. A life table gives information about: (a) Birth rates only (b) Mortality experience of a cohort from birth (c) Immigration patterns (d) Income distribution
Answer(b) Mortality experience of a cohort from birth Life table: shows the number of people surviving to each age from an initial cohort of l₀ (usually 1,00,000 = radix). Columns: lx (survivors), dx (deaths), qx (probability of death), ex (expectation of life).
6. Standardised Death Rate (SDR) is used to: (a) Measure infant deaths (b) Compare death rates between populations with different age structures (c) Calculate birth rate (d) Measure migration
Answer(b) Compare death rates between populations with different age structures SDR adjusts CDR for age distribution, making populations with different age structures comparable. Uses a standard population as weight.
7. Life expectancy at birth (e₀) represents: (a) Maximum possible age (b) Average number of years a newborn is expected to live (c) Average age of death (d) Number of deaths in a year
Answer(b) Average number of years a newborn is expected to live e₀ = T₀/l₀. Calculated from the life table. High e₀ indicates good health and living standards. Global average ~73 years; India ~70 years (2023).
II. Short Answer Questions
Q1. Calculate the Crude Birth Rate and Crude Death Rate from the following:
Answer
Population = 5,00,000; Live births = 15,000; Deaths = 6,000.
CBR = (15,000 / 5,00,000) × 1000 = 30 per 1000
CDR = (6,000 / 5,00,000) × 1000 = 12 per 1000
Natural Growth Rate = CBR − CDR = 30 − 12 = 18 per 1000
Q2. Why is Crude Death Rate considered a crude measure? What is the alternative?
Answer
CDR is "crude" because it lumps together all age groups without considering age structure.
Problem: An older population (more elderly people) will naturally have a higher CDR even if health standards are the same as a younger population.
Alternative: Standardised Death Rate (SDR) uses a standard population's age distribution as weights:
SDR = Σ(Age-specific death rate × Standard population weight) / Σ(Standard population weight)
SDR allows fair comparison between populations with different age structures.
Exam Checklist
- CBR = (births/population) × 1000; CDR = (deaths/population) × 1000.
- IMR = (deaths under 1 year / live births) × 1000 — indicator of healthcare quality.
- GFR uses women aged 15-49; TFR = Σ(ASFR) × 5.
- NGR = CBR − CDR.
- SDR adjusts for age structure; used for comparing populations.
- Life table: lx (survivors), qx (death probability), ex (life expectancy).
