Geographical Information Systems (GIS)

Purpose

Geographical Information Systems can be many things to many people. In general GIS are computer programmes which allow for the processing of spatial data into information, generally information which refers explicitly to, and is used to make decisions about some portion of the earth.

Application

GIS is an advanced and costly spatial analysis tool which should only be applied:

• if the spatial dimension of an issue is crucial (i.e. only if it is relevant).
• if the spatial situation is highly complex and if the interrelationship of many spatial factors is of importance (i.e. only in case it is necessary and advantageous compared to simple tools of spatial illustration).
• if you have the necessary data in a spatially disaggregated form, and if these data are sufficiently accurate and reliable (i.e. only if application is possible).

Description

GIS makes it possible to input many different types of data and link them to different aerial units, for example a school, village, town district, province etc. 
GIS can display data in different formats such as maps, graphs and tabular formats such as spreadsheets.
Although GIS is commonly used to create spatial representations (maps) it is able to manipulate geographical data to produce new information either by running statistical processes on the data or by combining different data sets to produce derivatives of data set relationships.

What is needed in order to use a GIS?

It is important to note that GIS is a system, if certain parts are missing the system will not run as well as it should. In order to set up a GIS there are eight main components:

1. A need for the outputs that GIS can provide! If you do not have a need do not consider a GIS.
   
2. The backing from your management structure, in terms of management support, financial support and human resources.
   
3. A champion for the GIS if you do not have a dedicated person willing to set-up and run the GIS it will not work.
   
4. GIS software (there are many on the market, including amongst others ESRI products, Intergraph, MapInfo. See the information links at the end for more information). It is important that the software you buy has the functionality to perform the tasks you want done. It is always a good idea to perform a user requirement analysis before you start your GIS so that money is not wasted buying a system that might have to be replaced in the short or medium term.
   
5. Hardware: such as a computer to run your software and peripherals such as printers for output.
   
6. Data: Geographical and attribute data. There are many methods of obtaining this data including primary (where you collect the data) or secondary methods (the Surveyor General, Consultants or information products mentioned in the toolbox such as the PIMSS CD).
7. The skills to use the hardware and software.
   
8. A process to ensure that the information you want from the GIS does not become outdated.

What to look out for when outsourcing your GIS?

Although you may have good relations with your GIS consultant there are a few precautions that you should take.

• When outsourcing it is critical to make sure to whom the data belongs, as well as what system is used (some GIS are not compatible with other types and converting data can be an expensive process). Do not pay for the collection of data you do not own. Do not get locked into a particular company through a badly worded legal document.
  
• Know what you are paying for, get the consultant to break down the costs into data collection and cleaning, processing, outputs and labour, do not pay more than you need to for data which is freely available.
  
• Insist on a metadata file of all the data included in the GIS and the processes that were used to derive the data. It may seem like a lot of trouble to go though initially but it will save money in the long run.
  
• Insist on a copy of the data even if you do not have a GIS. You may use another company next time and data is hard to get out of previous contractors.

Source

PIMSS: IDP Guide 4, Toolbox Part 2 (PIMSS-Net, Guides & Tools Centre)

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