DATA VISUALIZATION

Data visualization

Data visualization refers to the techniques used to communicate data or information by encoding it as visual objects (e.g., points, lines or bars) contained in graphics.

A primary goal of data visualization is to communicate information clearly and efficiently to users via the information graphics selected, such as tables and charts. Effective visualization helps users in analyzing and reasoning about data and evidence. It makes complex data more accessible, understandable and usable. Users may have particular analytical tasks, such as making comparisons or understanding causality, and the design principle of the graphic (i.e., showing comparisons or showing causality) follows the task. Tables are generally used where users will look-up a specific measure of a variable, while charts of various types are used to show patterns or relationships in the data for one or more variables.

Data Visualization Techniques should:

·         show the data

·         induce the viewer to think about the substance rather than about methodology, graphic design, the technology of graphic production or something else

·         avoid distorting what the data have to say

·         present many numbers in a small space

·         make large data sets coherent

·         encourage the eye to compare different pieces of data

·         reveal the data at several levels of detail, from a broad overview to the fine structure.

·         serve a reasonably clear purpose: description, exploration, tabulation or decoration.

·         be closely integrated with the statistical and verbal descriptions of a data set.

Two primary types of information displays are tables and graphs.

·         A table contains quantitative data organized into rows and columns with categorical labels. It is primarily used to lookup specific values. In the example above, the table might have categorical column labels representing the name (a qualitative variable) and age (a quantitative variable), with each row of data representing one person (the sampled experimental unit or category subdivision).

·         A graph is primarily used to show relationships among data and portrays values encoded as visual objects (e.g., lines, bars, or points). Numerical values are displayed within an area delineated by one or more axes. These axes provide scales (quantitative and categorical) used to label and assign values to the visual objects. Many graphs are also referred to as charts.