What are Geographical Information Systems (GIS) & ArcView GIS software?

• What is a Geographical Information System (GIS)?

• Introduction to ESRI ArcView 3.x

• Social science / population geography relevant GIS procedures

Paul Norman

• Cathie Marsh Centre for Census & Survey Research

• paul.norman@manchester.ac.uk

GIS that the Victorians did for

us!

Charles Booth (poverty maps, 1898-9)

John Snow, (cholera, 1854)

Asthma rates & main roads

Violent crime & deprivation

21st Century GIS

GIS definitions

• GIS A computer system for the input, storage, editing, manipulation, transformation, analysis and output of spatial data

• GIS is (effectively) either an overarching way of organising your spatial data or software for carrying out the above

• Spatial data Data with some form of geographical reference that enables it to be located in two (or three) dimensional space e.g. a grid reference or administrative area code

What can I use GIS for?

• Basic GIS functionality:– Spatial data input and management– Combining datasets (linked by location)– Output (e.g. drawing pretty maps)

• Socio-demographic data:– Distributions of population-related

phenomena (e.g. mapping SMRs)

GIS ‘vector’ & ‘raster’ models

• Vector (e.g. ArcView)– Geometric Cartesian (xy) co-ordinates

• Including projection information• Longitude/latitude, National Grid

– Maps world as discrete graphic features • Points, lines & polygons

– Links to a database for ‘attribute’ storage • Age, sex, deprivation score, area code

• Raster (pixel based, not basic ArcView)– Used for images, environmental data

GIS vector model

Points?

• Houses

• Hospitals, schools

• Cancer cases

• Crime incidents

• Mobile phone masts

• Postcodes

(Some ‘buts’ in a minute!)

Lines?

• Roads

• Footpaths

• Rivers

• Railways, canals

• Pipelines, cables

Polygons?

• Administrative boundaries

• Lakes

• Buildings

• Urban extents

England & Wales

Government Office Region

Wards

Local Authority District

Output Areas

Administrative & Census geographies

But … points, lines & polygons

• Scale dependent– Buildings / Cities: points or polygons?– Postcodes: points, lines or polygons?

Vector GIS digital data

Text files of lists of xy coordinates

• Points = single NGRs

• Lines = lists of NGRs

• Polygons = lists of NGRs that form a loop that knows it’s a loop!!

Polygons with common boundaries are listed separately

ArcView not very clever at topology

Attribute data

• Database (in .dbf format for ArcView)

ArcView 3.x GIS

• Vector-based GIS• Windows GUI environment:• Help system• Task-specific menu & button availability• Extensions for more functionality

Other software …• ArcInfo• MapInfo

Project window

• Views (maps)

• Tables (database)

• Charts (graphs)

• Layouts (printables)

• Scripts (automation)

View window for mapsMenus, buttons

Symbol window

Themes = Shape files = maps Scale, NGR

Layered themes

Zoom

‘Table’ = database of attributes

Records

Fields

Menus, buttons

‘Layout’ = printable mapMenus, buttons

GIS procedures relevant to social sciences & population geography

• Creating thematic / choropleth maps

• Clipping & intersecting polygons

• Point in polygon

Creating a choropleth map in ArcView

Calculate results …

Unique area code to join data to digital boundaries

Creating a choropleth map in ArcView

What do I need to create a map in ArcView?

Digital boundary data:

• UKBORDERS http://edina.ac.uk/ukborders/ using Athens password or ONS CD for Census or ask!

• Extract geographical scale of interest

Some results (e.g. Census data from Casweb):

• Text file (comma or tab delimited) but with .txt extension. Or …

• Dbf file

• Must have alphanumeric codes that match the digital boundary area codes (& match for time & definitions)

Attach results to digital boundaries & make pretty map!

More examples … health

More examples … deprivation

More examples … total fertility rate

More examples … voter turnout

Clipping & intersecting polygons …

Clipping & intersecting polygons …

Change in legal definitions

Blue = 1991

Red = 2001

Point in polygon

Individual level data, located by postcode (points)

Attach NGRs from a directory

• Postcode enumeration district directory

• All fields postcode directory

Which polygon does each point lie within?

Can attach contextual information (e.g. ward deprivation scores) to individual data

Point in polygon

In which ward does each postcode lie?

Haldens ward 1991(•)

Another point routine …

Distance from one point to all others

GIS within CCSR

If you think you’re going to …

• Organise, manipulate, join spatial data

• Illustrate some results using a map

Ask & I’ll help

Always retain geographical reference codes (even if not using GIS software)

Short course?

• GIS for Social Science & Population Geography