Vector boundaries and population figures for 1981 for the Enumeration Districts of Great Britain

Table ID:

ENUMD_1981_GB     (1247721)

Contents:

Vector boundaries and population figures for 1981 for the Enumeration Districts of Great Britain

Approx. number of rows:

130,048

Table type:

Raw Data

Documentation Author:

Paula Aucott

Chronology:

The data are for the single year 1981.

Sources:

1. The polygons and identifiers for 1981 were obtained via the Census Geography service provided by the UK Data Service Census Support (formerly known as the Edina UKBorders service).
2. The 1981 population figures were obtained via Casweb, a service provided by the UK Data Service Census Support. This service gives access to historical aggregated census statistics for Great Britain between 1971 and 2001.

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Notes:

1. In 1981 Census data for England and Wales and Scotland were collected as Enumeration Districts.
2. In England and Wales the statistical data were disseminated using the same Enumeration Districts as used for data collection. However in Scotland Output Areas were created for disseminating data which do not match exactly with Enumeration Districts. The Office for National Statistics identify that the unit types are different (http://www.ons.gov.uk/ons/guide-method/geography/beginner-s-guide/census/output-area--oas-/index.html) but enquiries at MIMAS and EDINA failed to discover a look-up table, and these services had previously not been aware of the difference between the two datasets. It was established that there were nearly the same number of rows in the statistics (17,767) as in the polygons when merged by label to create multi-polygons (17,711). A quick glance through the statistical data IDs revealed all the rows matched the polygons except where the zone label included the letter code 'SS'. There appears to be one of these rows for each district, all with the OutputArea Code '01'. Often these rows have no statistics, but where they do they are not in the totals. We can only assume these rows relate to shipping and other similarly unusual non-permanent units, and which did not have an identifiable geographical area.
3. The statistical data were linked to the polygon data via the "join data" function using the "join attributes from a table" option on the unit "Label" (England and Wales) or "Zone_ID" (Scotland) in ArcGIS. The resulting temporarily joint table was then exported to a new permenant polygon coverage including these datasets. The statistical data contained units such those identified as "shipping" which did not correspond to any polygon area and consequently could not be matched up and included with the polygons in ArcGIS.
4. The polygon data file was a compilation of three separate files, enuermation districts for England, for Wales and for Scotland using the Geo-processing > merge function in ArcGIS.
5. This permanent coverage was subsequently re-projected from the British national grid via WGS84 to the preferred projection of the EU, ETRS89 LAEA (Lambert Azimuthal Equal Area) in ArcGIS using the Data Management Tools > Projections and Trasnformations > Feature > Project function. When loaded into postgres it was loaded as etrs89 LCC (Lambert Conformal Conic) Projection to coincide with the other etrs89 geometric objects in the database.
6. The EU's preference was for counts of 'Usually Resident', but this was not available for some earlier years therefore we have included both 'Persons Present' and 'Usually Resident' wherever possible.
7. The area for each polygon was generated using the 'Calculcate Geometry' function in ArcGIS.

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Checking:

1. The original data supplied by the UK Data Service were not checked other than making sure each polygon matched a row in the statsitical data.

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Indices:

Index	Type	Column(s) indexed
enumd_1981_gb_pkey	Primary key	gid
enumd_1981_gb_g_foot_etrs_gist		g_foot_etrs

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Constraints:

The table has the following associated constraints:

Constraint	Type	Details
enumd_1981_gb_pkey	Primary Key	See details above for primary key index
enforce_dims_g_foot_etrs	Check	((st_ndims(g_foot_etrs) = 2))
enforce_geotype_g_foot_etrs	Check	(((geometrytype(g_foot_etrs) = 'MULTIPOLYGON'::text) OR (g_foot_etrs IS NULL)))
enforce_srid_g_foot_etrs	Check	((st_srid(g_foot_etrs) = 3034))

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Columns within table:

Column	Type	Contents
gid	Integer number.	Unique row identifier
zone_label	Text string (max.len.=24).	Enumeration District or Output Area ID number defined by ONS or GROS as supplied.
ed_area_sqm	float8	Area of polygon in square metres, calculated by us in ArcGIS from the polygon.
all_pres_res	Integer number.	Residents present within the Enumeration District/Output Area in 1981.
abs_res	Integer number.	Residents absent within the Enumeration District/Output Area in 1981.
all_visitors	Integer number.	All visitors within the Enumeration District/Output Area in 1981.
pers_present_71	Integer number.	Persons present within Enumeration District/Output Area in 1981, based on 'Present residents' and 'Visitors'. This is the baseline for the equivalent of the population present figure in 1971.
pers_present_81	Integer number.	Persons usually resident within Enumeration District/Output Area in 1981, based on 'Present residents' and 'Absent residents'. This is baseline for the equivalent of the population usually resident figure in 1981.
g_foot_etrs	geometry	Boundary polgon, as supplied by the UK Data Service.
eactive_1981	Floating point number.	Persons aged 16-64 in 1981 who were economicaly active.
eactive_1981_unem	Floating point number.	Persons aged 16-64 in 1981 who were economicaly active but not employed.