T HE W EB - BASED I NTERFACE TO C ENSUS I NTERACTION D ATA - WICID Presentation to the ESRC Research Methods Festival Adam Dennett Centre for Interaction Data Estimation and Research School of Geography University of Leeds

P RESENTATION O UTLINE Brief background to interaction data access The requirements and design of the WICID interface System architecture and metadata Accessing WICID and basic interface functions Advanced interface functions Future developments

T HE A CCESS P ROBLEM For many years access to interaction data was not straightforward. The evolution of computer technology made access easier, but not easy. Programmes such as MATPAC, SMSTAB, SWSTAB and QUANVERT; powerful tools but not user friendly – command-line driven. In order to encourage wider usage through facilitating easy access to the data, the Web-based Interface to Census Interaction Data (WICID) was constructed. Background to interaction data access

WICID WICID was designed with a number of specific requirements in mind: 1.The interface must be user friendly. It must facilitate query building, quick data extraction and simple downloading of files by non-expert users. 2.The interface should provide access to library of popular data sub-sets and their associated pre- defined queries. 3.The interface must be flexible to allow for the addition of new datasets Interface design and requirements

WICID 4.Where flows can be measured between multiple origins and destinations of differing sizes, the selection of geographies should be made as simple as possible 5.Users should be assisted in building queries through the provision of alternative variable selection methods 6.The system (if not the data contained) should be made available to other parties, thus should be constructed though free/open source components Interface design and requirements

WICID System architecture and metadata Web browser client: IE, Firefox, Opera, etc… Web browser client: IE, Firefox, Opera, etc… Web server: Apache , supporting php 5 Web server: Apache , supporting php 5 Database Server: PostgreSQL Session Data Interaction Data Meta Data User View Web server DBMS

WICID Underpinning the whole system are the three datasets held within the DBMS: Interaction datasets and their associated geographies are clearly fundamental. WICID stores various tables from: – Special Migration Statistics (SMS) Special Workplace Statistics (SWS) and Special Travel Statistics (STS) at a variety of geographical scales from 1981, 1991 and 2001 Censuses. – Geographical data and look-up tables also stored Metadata are equally fundamental as the system has no ‘hard-coded’ data; without these data in place to describe the interaction data to the system, WICID would not be able to function Session data are used by the system to remember which options have been selected by users during the query process – key in a system with multiple pages and options System architecture and metadata

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WICID Basic Interface Functions

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WICID As well as the standard query building interface functions, WICID offers a selection of additional features: – Downloading of population data with flow data – Facility to derive new variables from existing variables – Analysis functions – Customised help system Additional Interface Functions

WICID PAR data are required for rate calculations. Where comparable PAR are available for flow data, WICID will find and add these data to the selection for download WICID will aggregate PAR data to exactly the same level as the selected origins or destinations, thus allowing for simple post- extraction calculations to be made Populations at Risk

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WICID The derive option allows users to create new aggregate variables from those already in existence in the SMS and SWS tables. The derive function is particularly useful where there may be too much disaggregation in the original data e.g. all 7 ethnic groups could be re-aggregated into just ‘white’ and ‘other ethnic groups’ categories before download Deriving new variables

After selecting variables, clicking the ‘derive’ link underneath the table allows any of the chosen variables to be combined into a new variable e.g or etc.

WICID WICID has a suite of analysis functions which can be used to interrogate extracted data (either for the entire matrix, in-flows or out-flows), these include: Basic statistics – Min, Max, Mean, Median, Sample standard deviation, Coefficient of variance. Correlation statistics Distance travelled (mean or median for each variable) Indices of connectivity and inequality Index of migration effectiveness Crude intensities (in/out migration rates and matrix rate) Analysis functions

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WICID WICID’s inbuilt flexibility means that it will easily be able to incorporate additional (Census and non-Census) datasets as and when they become available. The only requirement is that future data follow the origin/destination/variable format. Current data have arrived for discrete time periods, in future there is no reason why more continuous interaction data could not be added in an origin/destination/variable/time reference format. Prior to the release of 2011 Census data, WICID will be providing access to annual patient registration/NHSCR data from 2001 at Health Authority level. An on-going programme of minor interface updates and improvements Future developments