Creating a classification of workplace zones (COWZ)

Samantha Cockings, David Martin, Andrew HarfootGeography and Environment, University of SouthamptonUKDS Census Conference, Manchester, July 2015

Why create COWZ?• Geodemographic/area classifications very useful for broad range of applications e.g. retail, health, education, transport

• Existing classifications (official and/or commercial) mainly based on residents, households, residential areas e.g. OAC, urban/rural, built‐up areas

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Why create COWZ?• Geodemographic/area classifications very useful for broad range of applications e.g. retail, health, education, transport

• Existing classifications (official and/or commercial) mainly based on residents, households, residential areas e.g. OAC, urban/rural, built‐up areas

• Some socio‐economic/employment in OAC but nothing specifically focused on workers and workplaces

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An opportunity: Workplace Zones• New output geography designed specifically for release and analysis of workplace‐related data

– WZ boundaries: released January 2013

– WZ data: May 2014

• Much wider range of variables released in 2011 than 2001

• More appropriate geography for mapping and analysis 9

Workplace data: 2001 v 2011 

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2001: OAs 2011: WZs 2011: WZs

Age Population density Welsh language skills * 2

NS‐SeC Sex by single year of age Religion

Approximated social grade Ethnic group Passports held

Distance travelled to work Country of birth General health

Highest level of qualification Tenure – people

Employment status Occupation

Hours worked Length of residence in the UK

Industry

NS‐SeC

Approximated social grade

Distance travelled to work

Method of travel to work

Main language

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2011OutputAreas

Contains National Statistics data © Crown copyright and database right 2013Contains Ordnance Survey data © Crown copyright and database right 2013© OpenStreetMap contributors

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2011WorkplaceZones

Contains National Statistics data © Crown copyright and database right 2013Contains Ordnance Survey data © Crown copyright and database right 2013© OpenStreetMap contributors

Objectives• Develop a geodemographic classification of workplace zones (COWZ)

– Based on characteristics of workers and workplaces

– Using 2011 Census data

– Initially for England and Wales (currently no WZs in Scotland or N Ireland)

– Methods consistent with other classifications (OAC)

– Transparent, reproducible, updateable 13

Methods• Define key domains

• Select initial candidate variables

• Exploratory analysis/refinement of variables

• Transform and standardise variables

• Undertake clustering

• Evaluate outputs from clustering

• Refine variables/clustering as necessary

Domains• Composition of workplace population

• Composition of built environment

• Socio‐economic characteristics of workplace population

• Employment characteristics of workplace population

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Exploratory analysis• Small numbers/populations

• “Uninteresting” distributions

• Highly correlated variables

• “Badly behaved” distributions

• Composite variables

• Data quality issues

• Consistency of variable use in future censuses

Transformations• 2001 OAC: log [Vickers & Rees, 2007]

• 2011 OAC: inverse hyperbolic sine (IHS) [Gale, 2014]

• We evaluated: log, IHS, Box‐Cox

• Box‐Cox performed best overall

– Positively skewed distributions

– Large number of zero counts

– Responsive to specific distribution of variable

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Transformations

WP703EW: Method of travel to work: bicycle or on foot

Correlations

Variable sub‐setting• 504 initial candidate variables

• 63 chosen for further examination

• 48 selected for final input to the clustering algorithm

• Range standardisation applied before clustering

Variable code Variable nameComposition of workplace populationWP102_WPPOPDENS Workplace population density (number of persons per hectare)WP1101_F_16_74 All categories: Age 16 to 74, FemalesWP1101_F_25_39 All categories: Age 25 to 39, FemalesWP1101_MF_16_24 All categories: Age 16 to 24, All categories: SexWP1101_MF_GE60 All categories: Age 60 to 74 , All categories: SexWP201_Black Black: African/Caribbean/Other BlackWP201_In_Pk_Bng Asian/Asian British: Indian, Pakistani, BangladeshiWP201_WhiteBrit White: English/Welsh/Scottish/Northern Irish/BritishWP203_EU_2001_11 Europe: Other Europe: EU countries: Accession countries April 2001 to March 2011: Total

WP203_EU_pre2001 Europe: Other Europe: EU countries: Member countries in March 2001: TotalComposition of built environmentOAWZRATIO Ratio of output areas to workplace zonesSocio‐economic characteristics of workplace populationWP501_GE_L4 Level 4 qualifications and aboveWP501_L3 Level 3 qualificationsWP501_NoQual No qualificationsWP607_1 1. Higher managerial, administrative and professional occupationsWP607_2 2. Lower managerial, administrative and professional occupationsWP607_3 3. Intermediate occupationsWP607_5 5. Lower supervisory and technical occupationsWP607_6 6. Semi‐routine occupationsWP607_7 7. Routine occupationsWP702_GE20 20km and overWP702_LT5 Less than 5kmWP702_NoFixedPl No fixed placeWP702_WkFromHome Work mainly at or from homeWP703_PubTrans Underground, metro, light rail or tram, Train, Bus, minibus or coachWP703_Walk_Bike Bicycle, On foot

Variable code Variable nameEmployment characteristics of workplace populationWP601_Emp Employee: Full or Part‐timeWP601_FT_Stud Full‐time studentWP601_SEmp_w_E Self‐employed with employees: Full or Part‐timeWP601_SEmp_wo_E Self‐employed without employees: Full or Part‐timeWP604_FT_GE49 Full‐time: 49 or more hours workedWP604_PT_16_30 Part‐time: 16 to 30 hours workedWP604_PT_LE15 Part‐time: 15 hours or less workedWP605_A A Agriculture, forestry and fishingWP605_B B Mining and quarryingWP605_C C ManufacturingWP605_D_E D Electricity, gas, steam and air conditioning supply / E Water supply; sewerage, waste management and 

remediation activitiesWP605_F F ConstructionWP605_G_L G Wholesale and retail trade; repair of motor vehicles and motor cycles / L Real estate activities

WP605_H H Transport and storageWP605_I I Accommodation and food service activitiesWP605_J J Information and communicationWP605_K K Financial and insurance activitiesWP605_M M Professional, scientific and technical activitiesWP605_O O Public administration and defence; compulsory social securityWP605_P P EducationWP605_Q Q Human health and social work activitiesWP605_R_S R,S Arts, entertainment and recreation; other service activities

Clustering• Hierarchical  k‐means clustering technique (SED) – as per OAC

• Generate supergroups

– We explored 2‐12

• Generate groups from supergroups

– Explored 2‐6 for supergroups 5‐8

• Evaluation:

– Compactness of solution– Homogeneity of cluster size– Robustness– Characteristics of clusters– Ground‐truthing: ’Does it make sense on the ground?’

Evaluation of “best” number of clusters

Compactness of cluster solution relative to number of clusters

Steeper = “better”

Homogeneity of cluster size relative to number of clusters

Lower = “better”

Robustness

COWZ hierarchy

• 7 supergroups• 29 groups

[NB. No subgroup level]

E&W: 7 supergroupsSupergroup Supergroup name WZs

(count)WZs(%)

Area (km2)

Area (%)

Workplace population (count)

Workplace population (%)

1 Retail 5786 11 941 0.6 2679822 10.1

2 Top jobs 5183 10 604 0.4 3875226 14.7

3 Metro suburbs 8386 16 3231 2.1 3388398 12.8

4 Suburban services 10046 19 7993 5.2 3866746 14.6

5 Manufacturing and distribution

7417 14 6450 4.2 4484145 17.0

6 Rural 10858 20 132124 85.7 4050292 15.3

7 Servants of society 5902 11 2830 1.8 4069578 15.4

Total 53578 100 154174 100.0 26414207 100.0

E&W:supergroups

London:supergroups

Cardiff/Bristol:supergroups

29 groupsRetail1.1 Low density retail and wholesale1.2 Market squares1.3 Multicultural urban high streets1.4 Traditional high streets1.5 Shop until you drop1.6 Eat, drink, shop and be merry

Manufacturing and distribution5.1 Mining and quarrying facilities5.2 Industrial units5.3 Business parks5.4 Manufacturing, energy and utilities

Top jobs2.1 Global business2.2 Administrative centres2.3 Big city life2.4 Regional business centres2.5 Science and business parks

Rural6.1 Rural with core services6.2 Rural with non‐local workers6.3 Rural with mining or quarrying6.4 Traditional countryside

Metro suburbs3.1 Metro suburban distribution3.2 Cosmopolitan metro suburban mix3.3 Independent professional metro services3.4 Suburban metro infrastructure

Servants of society7.1 Large scale education7.2 Public administration7.3 Major hospitals7.4 Highly qualified workforces and professional 

servicesSuburban services4.1 Non‐metropolitan suburban areas4.2 Primarily residential suburbs

London: groups

Cardiff: groups

Examples of profiles

Examples of profiles

Examples of profiles

Observations

• Workplace zones/data robust: providing excellent new insights into characteristics of workers and workplaces

• Clear statistical and spatial patterns evident• Distributions more skewed than residential?• Weighting of worker v workplace characteristics• NB All names provisional at this stage

Limitations

• All usual limitations of Census data• Workplace data ‐ known inaccuracies• Census not a register of workplaces• Some possible artefacts e.g. PO Boxes, no fixed place of work, HQ addresses etc.

• Excludes cross‐border flows• Choice of variables, transformation, number of clusters: an art and a science!

• Only Census data – others need evaluation e.g. IDBR

Now and next …• Evaluation of E&W version of COWZ by key users• Produce UK version of COWZ

– ONS producing WZs for Scotland and NI– Data ready; apply same methods– Evaluate differences in variables, resolution, thresholds, distributions, correlations

– Will any Scot/NI‐specific classes emerge?– Release UK‐wide version of COWZ (unless E&W, Scot, NI versions more appropriate)

• Analysis: COWZ v other variables and data

ReferencesMartin D, Cockings S, Harfoot A, 2013, Development of a Geographical Framework for Census Workplace Data, Journal of the Royal Statistical Society, Series A 176 585‐602

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AcknowledgementsFunding: ONS, Quality Improvement Fund (QIF).

Contains public sector information licensed under the Open Government Licence v2.0. Contains National Statistics and Ordnance Survey data © Crown copyright and database right 2013. Contains data made available under the Open Database Licence and licenced as CC BY-SA © OpenStreetMap contributors.

Contact

s.cockings@soton.ac.ukTel: 023 8059 5519http://www.southampton.ac.uk/geography/about/staff/sc19.page?