Population and Social Development Factors

The Dependency Ratio

How many workers does it take to financially support one retired person or child? The dependency ratio measures the pressure on the productive part of a population. It compares the number of dependents (aged 0–14 and 65+) against the working-age population (aged 15–64).

Worked Example

Calculate the dependency ratio for a country where 30% of the population is young, 10% is old, and 60% is of working age.

$$\text{Dependency Ratio} = \frac{(\text{Young} + \text{Old})}{\text{Working Age}} \times 100$$

Step 1: Identify the percentage values for each group.

• $\text{Young} = 30$, $\text{Old} = 10$, $\text{Working Age} = 60$

Step 2: Substitute the values into the formula.

• $\text{Dependency Ratio} = \frac{(30 + 10)}{60} \times 100$

Step 3: Calculate the final answer.

• $\text{Dependency Ratio} = \frac{40}{60} \times 100 = 66.7$ dependents per 100 workers.

When birth rates fall, the dependency ratio decreases. In India, this ratio fell from 73% in 1990 to 47.5% in 2022. This shift creates a demographic dividend, where a proportionally larger working-age population can drive rapid economic growth.

Analysing Social Factors: Education and Inequality

A girl's ability to read a single sentence can completely change the shape of her country's population pyramid. Education is a primary driver of social development. Global literacy rates currently average 96% in developed countries, but only 65% in less-developed nations. Female education is the strongest predictor of falling fertility rates. In highly educated countries like the UK, the average age for first-time mothers is 32–33, compared to just 14–15 in low-literacy regions. This delay in childbirth physically narrows the base of the population pyramid. In India, government investment increased literacy from 48% in 1990 to 76% in 2023. This helped narrow the gender gap in literacy from 25% down to 7.7%, bringing the country closer to a perfect Gender Parity Index (GPI) in primary school enrollment.

Measuring Development: HDI and the Gini Coefficient

Money alone does not tell you how well people in a country are actually living. To evaluate a country's progress, geographers use the Human Development Index (HDI). It is a composite indicator scored from 0 to 1 that combines health (life expectancy), education (years of schooling), and standard of living (GNI per capita adjusted for Purchasing Power Parity (PPP)). HDI is superior to single metrics like GDP because it prevents averages from hiding poverty. For example, oil-rich nations might have high wealth but low social development, which HDI reveals. Countries are classified as Very High (e.g., UK 0.940), Medium (e.g., India 0.644), or Low (e.g., Niger 0.394). To measure internal inequality, we use the Gini coefficient, derived from the Lorenz curve. It measures income inequality on a scale of 0 (perfect equality) to 1 or 100 (perfect inequality). While the UK's overall Gini has been relatively stable at around 32.9% (disposable income) since the 1990s, the income share of the top 1% has increased. In India, rapid economic growth caused the Gini coefficient to rise from roughly 0.45 in 1990 to 0.51 by 2013.

Worked Example

Calculate the percentage increase in India's life expectancy from 1990 (58 years) to 2023 (72 years).

$$\text{Percentage Increase} = \frac{\text{Difference}}{\text{Original}} \times 100$$

Step 1: Calculate the difference.

• $\text{Difference} = 72 - 58 = 14$ years

Step 2: Divide the difference by the original value.

• $\text{Ratio} = \frac{14}{58} \approx 0.241$

Step 3: Convert to a percentage.

• $\text{Percentage Increase} = 0.241 \times 100 = 24.1\%$ increase over 30 years.

Social Mobility

You might assume that working hard guarantees a higher income than your parents, but in reality, your geographical location plays a massive role. Absolute social mobility occurs when an individual earns more or secures a higher-status job than their parents. In the mid-20th century, this was high due to an expansion of middle-class jobs, but it has recently slowed down. Sociologists also measure relative social mobility, which looks at how much an individual's background predicts their future success. In the UK, relative mobility has remained largely stagnant since the 1960s, heavily influenced by a regional "postcode lottery". Areas like London offer significant advantages, while coastal and old industrial towns like Middlesbrough have become mobility "cold spots". The economic impact is clear: in Reading, where 43% of people have degrees, professional workers earn around £700/week, compared to just £350/week for manual workers in Middlesbrough where only 19% have degrees.