Chapter 4
Per Capita & Per Unit Calculations
Total vs per-person values, population scaling, unit rate calculations
4.1 The per-capita formula
Total value = Per-capita value × Population Per-capita value = Total value ÷ Population Population = Total value ÷ Per-capita value
Example: 4 200 000 inhabitants, €1 800 per capita healthcare. Total = €1 800 × 4 200 000 = €7 560 000 000.
4.2 Keeping per-capita constant when population grows
New total = Old total × (1 + r/100)
Example: spending €4.2 billion for 7 million people. Population grows 3%. New total = €4.2 billion × 1.03 = €4.326 billion.
4.3 Per-unit rate problems
Per-unit rate = Total ÷ Number of units
The word 'per' always means division. Compare groups by their per-unit rate, never by absolute totals when groups are different sizes.