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What are Geographical Information Systems (GIS) & ArcView GIS software? What is a Geographical Information System (GIS)? Introduction to ESRI ArcView 3.x.

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Presentation on theme: "What are Geographical Information Systems (GIS) & ArcView GIS software? What is a Geographical Information System (GIS)? Introduction to ESRI ArcView 3.x."— Presentation transcript:

1 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

2 GIS that the Victorians did for us! Charles Booth (poverty maps, ) John Snow, (cholera, 1854)

3 Asthma rates & main roads Violent crime & deprivation 21 st Century GIS

4 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

5 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)

6 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

7 GIS vector model

8 Points? Houses Hospitals, schools Cancer cases Crime incidents Mobile phone masts Postcodes (Some buts in a minute!)

9 Lines? Roads Footpaths Rivers Railways, canals Pipelines, cables

10 Polygons? Administrative boundaries Lakes Buildings Urban extents

11 England & Wales Government Office Region Wards Local Authority District Output Areas Administrative & Census geographies

12 But … points, lines & polygons Scale dependent –Buildings / Cities: points or polygons? –Postcodes: points, lines or polygons?

13 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 its a loop!! Polygons with common boundaries are listed separately ArcView not very clever at topology Attribute data Database (in.dbf format for ArcView)

14 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

15 Project window Views (maps) Tables (database) Charts (graphs) Layouts (printables) Scripts (automation)

16 View window for maps Menus, buttons

17 Symbol window Themes = Shape files = maps Scale, NGR Layered themes Zoom

18 Table = database of attributes RecordsRecords Fields Menus, buttons

19 Layout = printable map Menus, buttons

20 GIS procedures relevant to social sciences & population geography Creating thematic / choropleth maps Clipping & intersecting polygons Point in polygon

21 Creating a choropleth map in ArcView Calculate results … Unique area code to join data to digital boundaries

22 Creating a choropleth map in ArcView

23 What do I need to create a map in ArcView? Digital boundary data: 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!

24 More examples … health

25 More examples … deprivation

26 More examples … total fertility rate

27 More examples … voter turnout

28 Clipping & intersecting polygons …

29 Change in legal definitions Blue = 1991 Red = 2001

30 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

31 Point in polygon In which ward does each postcode lie? Haldens ward 1991()

32 Another point routine … Distance from one point to all others

33 GIS within CCSR If you think youre going to … Organise, manipulate, join spatial data Illustrate some results using a map Ask & Ill help Always retain geographical reference codes (even if not using GIS software) Short course? GIS for Social Science & Population Geography


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