Data Preparation

What is the representation purpose?

Before beginning any work on the data, it is important that you know exactly what is the information you want to convey, to whom and why?
It is advisable in particular to deepen the knowledge of the readers for whom the map is intended, by defining at the same moment their "reading potential" and their interest for the treated subject.

Choice and manipulation of the data

Before proceeding to the cartographic representation of the data, it is necessary to choose which data to represent, and then to treat the data to make them capable of being represented on a map.

Data Preparation

Data preparation includes the following stages:

• Arrange the values into increasing order,
• Calculate some data information, such as:
  • The number of data (N)
  • The extreme values
  • Indications of descriptive statistics, such as mode, median, and average
  • Dispersal parameters: mean, co-variance and variance
• Complete this statistical information with graphs, such as
  • Distribution diagram
  • Histograms

Nowadays, various software (MS Excel for example), allow easy and fast data preparation.

Notice: the distribution diagram is the very basic data preparation you have to do. It will help you to choose the adequate classification method.