Plain-English glossary

age-standardised

Also written: age standardisation, age-adjusted

Populations differ in age, and age drives many outcomes: most prisoners are between 18 and 40, for instance. An age-standardised rate reweights each group to a common age profile so the comparison is not simply a comparison of age structures. Standardisation needs the underlying data split by age, which is often not published, so rates on this site are crude unless they say otherwise.

Crime Survey for England and Wales

Also written: CSEW, Crime Survey

The Crime Survey for England and Wales asks a large random sample of households about crimes they experienced in the previous year, including those never reported. Because it does not depend on reporting or recording practice, it is the more stable measure of long-run trends in offences such as theft and violence. It has its own limits: it does not cover homicide, offences against businesses, or crimes against people not living in a household, and being a survey it carries sampling uncertainty.

crude rate

A crude rate is the simplest possible comparison: how many events per 1,000 or 100,000 people. It is honest arithmetic but a blunt comparison, because the groups being compared may differ in age, in where they live, or in how often they come into contact with the system doing the counting.

local authority

Also written: local authorities, council area

A local authority is the council area responsible for services in a place. Boundaries change over time as councils merge, so figures shown here are placed on today's boundaries throughout, which is why a long series for an area may not match a figure published under an older boundary.

LSOA

Also written: Lower layer Super Output Area, Lower Super Output Area

A Lower layer Super Output Area is the smallest geography most official statistics use. Each holds about 1,000 to 3,000 residents and between 400 and 1,200 households. They exist so that figures can be published for small areas without identifying anybody. Their boundaries are redrawn after each census, which is why comparing an LSOA in 2011 with the same name in 2021 is not always comparing the same ground.

MSOA

Also written: Middle layer Super Output Area, Middle Super Output Area

A Middle layer Super Output Area sits between the LSOA and the local authority, holding roughly 5,000 to 15,000 residents. Many census tables are published at this level because the numbers are large enough to be reliable for small groups without disclosing information about individuals.

net migration

Net migration is long-term immigration minus long-term emigration over the same period. If 900,000 people arrive intending to stay a year or more and 600,000 leave, net migration is 300,000, and 900,000 people still arrived. A fall in net migration can therefore mean fewer arrivals, more departures, or both.

notifiable offence

Also written: notifiable offences

Notifiable offences are those forces are required to report to the Home Office. The list covers all indictable and triable-either-way offences plus some summary ones, but excludes many minor summary offences, so counts of notifiable offences and arrests for them are not counts of all police activity.

percentage point

Also written: percentage points

When a figure is itself a percentage, the difference between two values is measured in percentage points. A share moving from 10% to 15% has risen by 5 percentage points, which is a 50% relative increase. Confusing the two overstates or understates changes badly, so rates on this site always change in percentage points.

police force area

Also written: police force areas, force area, PFA

A police force area is the ground covered by one of the 43 territorial forces of England and Wales. Because police areas and council areas do not share boundaries, a figure published per force cannot be added up to a council area, or the other way round, without a lookup that maps between them.

police-recorded crime

Also written: recorded crime, police recorded crime

Police-recorded crime counts offences that reached a police force and were recorded under the Home Office counting rules. It is the only source fine-grained enough for individual offence types and small areas, but it moves with reporting behaviour and recording practice as well as with crime itself. A rise can mean more offences, more victims coming forward, or a force tightening how it records reports.

provisional

A provisional figure is published before the underlying returns are complete, so the publisher expects it to change. Civometry shows provisional figures as published and marks them, and keeps every version, so that when the number is revised you can see what it was before.

revision

Also written: revised

Statistical series are revised as late returns arrive or methods change. Because the old value usually disappears from the publisher's own site, Civometry stores every version of every figure, so a series can be read as it stood on any past date and revisions can be inspected.

usual resident

Also written: usual residents

The census counts usual residents: people who live in the UK for twelve months or more, or intend to. Short-term visitors are excluded. This is the population figure used as the denominator for rates on this site, which is why a rate can drift if a group has grown since census day.