Worked example · Geography · Year 10
DCF: Data and computational thinking → Data and information literacy
A secure Year 10 response, annotated against the success criteria, and your answer key. The data is real 2021 Census data, so these figures are the only correct ones. Key answers: warm-up 3.5% (Cardiff) and 6.6% (Conwy). Conwy's male column totals 48.6 and its female column 51.4. Dependency ratios are 48.6 (Cardiff) and 76.5 (Conwy). People aged 65+ make up 14.5% of Cardiff and 27.3% of Conwy. Accept answers that differ by 0.1 because of rounding.
Cardiff: 12,527 ÷ 362,312 × 100 = 3.5%. Conwy: 7,628 ÷ 114,741 × 100 = 6.6%.
The newspaper's numbers are right: Cardiff has 4,899 more women aged 70–79. But the claim is unfair, because Cardiff has more than three times as many people overall. Out of every 100 people, Conwy has almost twice as many women in their seventies as Cardiff does. To compare places of different sizes, you have to use percentages.
Both percentages are calculated from the right totals. The answer separates “more people” from “a bigger share of the people”. Evidences criterion 1.
| Age band | Males | Females | Males % | Females % |
|---|---|---|---|---|
| 90+ | 533 | 1,151 | 0.5 | 1.0 |
| 80–89 | 3,059 | 4,053 | 2.7 | 3.5 |
| 70–79 | 7,069 | 7,628 | 6.2 | 6.6 |
| 60–69 | 7,881 | 8,514 | 6.9 | 7.4 |
| 50–59 | 8,263 | 8,996 | 7.2 | 7.8 |
| 40–49 | 5,981 | 6,331 | 5.2 | 5.5 |
| 30–39 | 5,799 | 6,227 | 5.1 | 5.4 |
| 20–29 | 5,297 | 5,264 | 4.6 | 4.6 |
| 10–19 | 6,079 | 5,687 | 5.3 | 5.0 |
| 0–9 | 5,627 | 5,302 | 4.9 | 4.6 |
| All ages | 55,588 | 59,153 | 48.6 | 51.4 |
Working for one cell: females aged 50–59 = 8,996 ÷ 114,741 × 100 = 7.84, which rounds to 7.8. Check: 48.6 + 51.4 = 100.0.
Every percentage is a share of the whole population (114,741), which is why the two columns add up to 100 and the pyramid can be compared with Cardiff's. Evidences criterion 2.
Bars drawn to the same 1%-per-square scale as Cardiff's, so the two shapes can be compared by eye. The title names the place, the source and the year. Male and female bars differ in fill as well as colour, so it still works printed in black and white. Evidences criterion 3.
| Area | Dependency ratio | Aged 65+ as % of total |
|---|---|---|
| Cardiff | (65,995 + 52,499) ÷ 243,818 × 100 = 118,494 ÷ 243,818 × 100 = 48.6 | 52,499 ÷ 362,312 × 100 = 14.5% |
| Conwy | (18,378 + 31,368) ÷ 64,995 × 100 = 49,746 ÷ 64,995 × 100 = 76.5 | 31,368 ÷ 114,741 × 100 = 27.3% |
For every 100 people aged 16–64 in Conwy, there are about 77 children and people aged 65 or over. In Cardiff there are about 49. The difference is almost all at the older end: more than a quarter of Conwy's residents are 65 or over, nearly double Cardiff's share.
The working is shown, so each ratio can be checked. The sentence explains what the number means instead of just giving it. Evidences criterion 4.
(a) Cardiff's pyramid bulges in the middle. It is widest at 20–29 (9.1% male and 9.5% female, so 18.6% of everybody), then gets steadily narrower from 40 upwards, to only 1.3% and 1.9% at 80–89. Conwy's is top-heavy. It is narrowest among young adults (4.6% on each side at 20–29) and widest at 50–59 (7.2% and 7.8%). It stays wide through 60–69 (6.9% and 7.4%) and 70–79 (6.2% and 6.6%). So one in five people in Conwy is aged 70 or over.
(b) Cardiff is a capital city with several universities, so students move in at 18. Young adults also move there for first jobs in the Senedd, the Welsh Government, the NHS, the media and business. The term-time rule makes this bar even bigger: students were counted at their Cardiff address even if they were back home during lockdown. So some of those 20-year-olds were really sitting in their parents' houses, possibly in Conwy, on census day. That also helps explain why Conwy's 20–29 bar is so thin.
(c) Towns like Llandudno and Colwyn Bay attract people when they retire, for the sea, the scenery and a quieter life. At the same time, many young people leave for university and work. Conwy will need more health and social care, such as GP appointments, home carers and care home places, and more accessible transport and housing, such as buses with low floors and bungalows or adapted homes.
(d) In Conwy, 3.5% of the population are women aged 80–89 compared with 2.7% men. At 90+ it is 1.0% against 0.5%: 1,151 women and 533 men, more than two to one. On average women live longer than men, so the gap gets wider the older the age band.
(e) The pyramid shows how many people there are, but not why they are there. It cannot tell me whether Conwy's older people moved in at retirement or have always lived there. It is also a snapshot of one day, 21 March 2021, in the middle of a lockdown. To see change you need to put it next to the 2011 census. A third limit is the ten-year bands: they hide detail. For example, the 10–19 band mixes schoolchildren with 18- and 19-year-old students.
Each claim has one of the pupil's own figures attached. The explanations use migration for both universities and retirement. Part (b) spots how a census counting rule changes the data, and part (e) names limits of official data without saying it is wrong. Evidences criteria 4 and 5.