1.30460 · Section 1: Theme 1 — Population and settlement

Population structure

Key learnings

Reading a population pyramid
A population pyramid shows the AGE and SEX structure: age bands up the vertical axis, males left, females right, bar length = the % in each age-sex group. Three features carry meaning. The BASE WIDTH shows the recent BIRTH RATE. The SIDE SLOPE shows the DEATH RATE at each age -- steep sides mean most survive to the next band. The TOP WIDTH shows LIFE EXPECTANCY and the elderly population's size. Reading a pyramid means DESCRIBING these with the data, not explaining WHY.
The dependency ratio
The dependency ratio = the number of dependents (aged 0-14 plus 65 and over) per 100 people of working age (about 15-64). Formula: (young + elderly dependents) / working-age population x 100. Example: 40% aged 0-14, 54% aged 15-64, 6% aged 65+ gives (40 + 6) / 54 x 100 = about 85 per 100 workers. A HIGH ratio (many children, many elderly, or both) means fewer workers support more non-workers. It uses AGE bands only, not whether a person has a job.
Japan: an ageing population
Japan is the classic 7-mark case. Around 29% of its people are aged 65 or over -- among the world's highest -- while its birth rate has fallen below replacement level (high living costs, limited housing, women prioritising careers). Life expectancy is around 84 years, from advanced healthcare and diet. Consequences: a shrinking workforce and labour shortages, rising pension and healthcare costs, and responses such as a higher pension age and investment in robotics.

Common mistakes

Drawn from real examiner reports.

Triangular graph read vertically

A triangular graph shows three age-group percentages (0-14, 15-64, 65+) at once. Each variable has its OWN angled axis, so read a value along that variable's gridlines, not straight up the page. Reading vertically is the commonest error and can give a badly wrong figure -- about 25% when the correct value is nearer 15%. Identify the variable's axis before tracing it.

s23 P21 Q2(a)

'Pyramid' alone / unworkable graph type

Asked what OTHER graph could show population-structure data, weak answers pick a type that cannot work: a line or scatter graph cannot show three age-band percentages that add to 100%, whereas a triangular graph, divided bar or pie chart can. A second trap: if "population pyramid" is expected, writing just "pyramid" is not accepted -- the full term is needed.

w23 P23 Q2(a)

Compare between areas, not within one

A "compare" question on dependency ratio wants explicit statements linking BOTH areas (higher/lower, whereas). A common error is describing figures for only one area, or the two separately without relating them -- that scores far less than a genuine between-area comparison, even with every figure quoted. Mention both places in one sentence, with units.

w22 P11 Q1(a)(iii)

Dependency-ratio calculation slips

Two recurring slips wreck this calculation. First, dividing by the TOTAL population (100%) instead of only the WORKING-AGE band (15-64). Second, forgetting to ADD both dependent groups (0-14 AND 65+) before dividing. The formula is (young + elderly dependents) / working-age population x 100 -- isolate the 15-64 band as the denominator and sum the other two on top.

Dependency ratio ≠ unemployment

The dependency ratio is built purely from AGE bands (0-14 and 65+ as dependents, 15-64 as working age), NOT from who has a job. An unemployed working-age adult still counts as working-age, not a dependent; a 70-year-old who still works still counts as an elderly dependent. Do not adjust for real employment -- it is an age-structure measure, not an unemployment rate.

Say which group drives the ratio

A high dependency ratio does NOT automatically mean an ageing population -- it can come from many children, many elderly, or both. Always state WHICH group drives the figure and the pressure it creates: a youthful high ratio strains schools and child healthcare; an elderly one strains pensions and care. Naming the driver turns a number into a point.

Ageing population ≠ shrinking population

A testable wrong belief: that an ageing population must be shrinking. "Ageing" means a rising PROPORTION of elderly people -- a change in AGE STRUCTURE, not total SIZE. A country can age while still GROWING, if births exceed deaths or migrants arrive. Only after a low birth rate persists for years does the total shrink -- as has now begun in Japan.

Exam tips

Nail the 7-mark structure case study
On the 7-mark structure case study, name a REAL country (e.g. Japan). Cover BOTH the reasons for the structure AND its consequences, and LINK each reason to its effect ("high life expectancy, SO rising pension costs"). Only reasons, or only consequences, stays mid-band.
Describe vs explain a pyramid
Match the command word. DESCRIBE a pyramid = WHAT the shape shows, with figures. EXPLAIN = the REASONS why (birth rate, death rate, life expectancy). Explaining causes when describe is asked, or vice versa, scores nothing. Read whether it wants the pattern or the reason.
Back pyramid descriptions with data
Describing a pyramid, quote the actual figures -- the percentage in each band -- not just shape words like "wide base". Pair each feature with its data ("wide base, 42% aged 0-14"), and add comparative words when two structures sit side by side.

Revision notes

1. Key terms

Population pyramid -- a bar graph showing the age and sex structure of a population: age groups on the vertical axis, males on the left of a central line, females on the right, bar length showing % or number of people.
Age structure -- the proportion of a population found in each age group.
Dependency ratio -- the number of dependents (0-14 plus 65+) per 100 people of working age (15-64). Formula: (young dependents + elderly dependents) divided by working-age population, times 100.