f undamentals of g eographic d ata james stewart measure evaluation 15 février 2010 suivi et...

FUNDAMENTALS OFGEOGRAPHIC DATA

James STEWARTMEASURE Evaluation

15 février 2010

Suivi et Evaluation des programmes VIH/SIDA- Séminaire régional CESAG - Dakar, Sénégal 

MEASURE Evaluation is funded by USAID through

Cooperative Agreement GHA-A-00-08-00003-00 and is

implemented by the Carolina Population Center at the

University of North Carolina at Chapel Hill, in partnership with

Futures Group International, John Snow, Inc., Macro

International Inc., Management Sciences for Health, and

Tulane University. The views expressed in this publication do

not necessarily reflect the views of USAID or the United States

government.

Visitez-nous en ligne à http://www.cpc.unc.edu/measure.

General Objective

The general objective of the module

« Fundamentals of Geographic Data » is to present

the fundamentals of geographic data, including the

relationship between geographic and attribute data,

and to help participants understand some important

data quality considerations.

Session Plan

Coordinate systems and datums

Geographic data

Geographic identifiers

Data schema best practices

GeographicIdentifiers

Geographic Identifiers

GPS coordinate

Administrative name

In reference to other features

Geography basics

Latitude/Longitude

Taj Mahal: 27.17 Latitude 78.04 Longitude

GPS Coordinate

Global

Positioning

System

GPS Coordinates

Advantages Very accurate:

10 meters or less

Easy to get a quick location of a few objects

Receivers and devices becoming more affordable

Disadvantages If many objects need to

be located, there needs to be a well designed data collection protocol

Capturing something other than a point can add time and cost

GPS Coordinate

Best practice: Display as

latitude/longitude coordinate

Example:

36.05576

078.91376

Geographic Identifiers

Administrative division names or codes Regions, provinces, districts, communes

Human settlement names or codes

Cities, villages, neighborhoods, informal settlements

Exact locations

Street addresses, GPS coordinates

Geographic Identifiers: Administrative Divisions

Source: Odhiambo, Emma. “Census Cartography: The Kenyan Experience,” presented at the United Nations Expert Group Meeting on Contemporary Practices in Census Mapping and Use of

Geographical Information Systems, 29th May – 1st June 2007, New York.

Kenyan Geographic Hierarchy for 1999 Census

Acknowledgments:USAID, FEWS, EDC-International Program, andthe U.S. Geological Survey.

Source:Administrative boundaries downloadedOctober 2008 from http://gisweb.ciat.cgiar.org/povertymapping/.

Geographic Identifiers:Human Settlements

Cities

Towns

Villages

Neighborhoods

Communities

Informal settlements

Geographic Identifiers

Anything that helps uniquely identify where something is

Data SchemaBest Practices

Data Schema Best Practices:Data Dictionary

Data Schema Best Practices:Data Dictionary

Data Schema Best Practices:Data Dictionary

Data Schema Best Practices:Data Dictionary

Data Schema Best Practices:Example

Data Schema Best Practices:Example

Data Schema Best Practices:Example

Data Schema Best Practices:Summary

Use a data dictionary

Always include geographic identifiers

Require one record per row, one value per cell

Avoid missing values

Data Schema Best Practices:Summary

Related Assumptions

Data stored in electronic format

Paper-based records inhibit analysis

Data stored in spreadsheet or database

Word processing and PDF documents inhibit analysis

Data Schema Best Practices:Summary

Good Data Schema

Results in higher quality data

Facilitates linking and sharing of data

Strengthens the data infrastructure

Improves the decision-making process

MERCI

Discussion Questions

What geographic identifiers do you use in your country, and do they work well for the types of decisions you need to make?

What problems have you run into, if any?

Do you always include these geographic identifiers in your data?