FAQ & Glossary
Common questions about the data and key terms used across the site.
Frequently Asked Questions
Glossary
- Decile
- One-tenth of a population when sorted by a measure (e.g., wealth). The bottom decile is the poorest 10%, the top decile is the richest 10%.
- Percentile
- One-hundredth of a population. Being in the 90th percentile means you have more than 90% of the population.
- Net wealth
- Total assets (property, pensions, savings, possessions) minus total debts (mortgages, loans, credit cards).
- Household wealth
- The combined net wealth of everyone living in a household. Most UK wealth surveys measure at the household level.
- Median
- The middle value when all values are sorted. Half the population is above, half below. Less affected by extreme values than the mean.
- Gini coefficient
- A measure of inequality from 0 (perfect equality) to 1 (one person owns everything). The UK's total-wealth Gini is approximately 0.63 (ONS Wealth and Assets Survey).
- CPI (Consumer Price Index)
- A measure of inflation tracking the cost of a basket of goods and services. Used to convert nominal values to real terms.
- Capital gains
- Profit from selling an asset (property, shares, etc.) for more than you paid. Taxed at lower rates than income in the UK.
- Inheritance Tax (IHT)
- A 40% tax on estates above £325,000 (with a £175,000 residence nil-rate band). Only about 4-5% of deaths result in an IHT charge.
- Wealth and Assets Survey (WAS)
- The ONS's main survey measuring household wealth in Great Britain. Covers financial, property, pension, and physical wealth.
- WID (World Inequality Database)
- An academic database combining tax records and national accounts to estimate wealth and income distributions globally.
- ASHE
- Annual Survey of Hours and Earnings. The ONS's main source for earnings data, covering 1% of all UK employees via PAYE records.