Geographical referencing and the modifiable areal unit problem
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Geographical referencing and the modifiable areal unit problem. Geographical referencing and the MAUP. Lecture overview: Objectives of lecture Introductory questions Geographical referencing of social data Modifiable areal unit problem Lecture summary. Objectives.

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Geographical referencing and the maup
Geographical referencing and the MAUP problem

  • Lecture overview:

    Objectives of lecture

    Introductory questions

    Geographical referencing of social data

    Modifiable areal unit problem

    Lecture summary

Objectives problem

  • To understand that there are multiple options for the geographical referencing of social data

  • To be familiar with the principal datasets and approaches

  • To understand the representational difficulties associated with areal aggregation

Introductory questions
Introductory questions… problem

How do I find out which census area this postcode falls into?

What on earth is the modifiable areal unit problem??

Geographical referencing
Geographical referencing problem

  • Most commonly points and areas

  • Generally indirect

    • Census zones

    • Service delivery districts

    • Postal geography

    • Regular grid (esp. from RS modelling)

  • Aggregation from individuals

  • Arbitrary boundary location cf. phenomena of interest (‘imposed’ vs ‘natural’ areal units)

Point data
Point data problem

  • Precise location hard to determine

  • Usually indirect via home address elements (night-time/day-time)

  • Point pattern valuable, but mostly reflects population distribution

  • Many analysis concepts require aggregation (rates, denominators etc.)

Increasing spatial resolution
Increasing spatial resolution problem

  • Early census data – large zones

  • Smaller zones, service delivery areas

  • GIS manipulation of zonal data

  • Point referencing – indirect and direct

  • Which is the ‘correct’ spatial object for the representation of population-related phenomena?

Representational issues
Representational issues problem

  • Spatial representation is a process, not a single technical decision

    • Decisions ‘frozen’ in conventional cartography

    • Digital datasets make possible remodelling of the data, and linkage between datasets

  • Possible to think of the same entities as different types of spatial object

What kind of spatial object

Disease incidence problem

As points

As lines

As areas

What kind of spatial object?

As surface

Some uk address lists
Some UK address lists... problem

  • Postcode Address File (Royal Mail)

  • Council Tax Registers (local government/Valuation Office Agency)

  • National Land and Property Gazetteer (local government/Intelligent Addressing)

  • ADDRESS-POINT (Ordnance Survey)

Points address referencing
Points: address referencing problem

  • ~25m postal addresses

  • Increasing use of address-level referencing but difficulties achieving national standards (BS7666, Acacia)

  • 2001 census difficulties in Manchester and Westminster

    • 14000 ‘missed’ addresses added to Manchester 2003 mid-year estimate

Address matching problems

St. Andrews Rd problem

SO17 1BJ

Flat 3, 9 Winn Road


The Haven, Chalk Dr

1 Church Hill Drive

Lawn Place, SE15

Saint Andrew’s Road


9c Winn Road


379 Chalk Drive

1 Churchill Drive

Haslam Street, SE15

Address matching problems…

Ambiguous addresses
Ambiguous addresses problem

Photo: Dave Martin

<West Park, BS8 or Cotham Hill, BS6?>

Lookup tables
Lookup tables problem

  • Giving (population or household weighted) entity-to-entity relationships e.g. postcode to census output area

  • Independent from direct effects of imposed areal unit boundaries

  • May include coordinate references

  • Tools for cross-matching geographies

  • May be generated administratively or analytically

Lookup tables1
Lookup tables… problem

  • No sliver polygon or spatial mis-matching issues

  • May be the only alternative for modelling change over time for detailed geographies

  • Source of ancillary variable for areal interpolation (e.g. redistribute unemployment pro rata population counts)

Modifiable areal unit problem
Modifiable areal unit problem problem

  • Openshaw (1984)

  • Applicable to all imposed areal units

  • Scale and aggregation effects

  • Always impacts on spatial analysis

  • Effects often ignored

Maup illustrated
MAUP illustrated problem



MAUP problem

  • If we change the boundaries of an areal unit, would we alter the population ‘captured’ to the extent that we would change

    • Its geodemographic classification

    • Its position in a deprivation league table

Ecological fallacy
Ecological fallacy problem

  • Relationships observed in ecological data would not necessarily hold at other scales of aggregation

  • Relationships observed in ecological data do not necessarily apply at the individual level

Ecological data issues
Ecological data issues problem

  • Are all the people living in a deprived ward ‘deprived’?

  • Are all the people living in a ‘well-off retirees’ neighbourhood either well-off or retired?

    • Almost certainly not!

Lecture summary
Lecture summary problem

  • Ambiguity of geographical referencing

  • Different spatial data types

  • Multiple address referencing options

  • Lookup tables, particularly based on postcode geographies

  • Modifiable areal unit and ecological fallacy issues