Teaching:TUW - UE InfoVis WS 2006/07 - Gruppe 03 - Aufgabe 1 - Data Density

Definition

Data Density means the number of data points per area of the graph (that is the number of pixels in the display where number of pixels does not include the pixels in the window borders, menus, etc.).

[Brath, 1997]

Charts and Graphs

In The Visual Display of Graphical Information of Edward Tufte, a milestone in the theory of graph design, principles of graph design are discussed. One of them is: Try to maximise the data density. [Hunt and Mashhoudy, 2002]

While the human eye has the ability to detect large amounts of information within a very small area, statistical graphs often fail to take advantage of this ability. To messure the information content of a graph he definses the data density. [Hunt and Mashhoudy, 2002]

Example

To better undrestand this term, we show two two graphs and compute their data density. Consider the result of a survey in which the gender, height and weight were recordet for 92 students. Below you see a bar graph showing the breakdown into males and females. The charts are 5.6cm by 7.4cm, an area of 41.4cm2. [Hunt and Mashhoudy, 2002]

According the definition you've 2 (female and male) areas with 2 kinds of information (gender and number of students), what makes 4 data points. By deviding this over the size of its area, you get the data tensity of this graph.

number of data points = 4 data density = 4 / 41.4 = 0.1 (to 1 dp) [Hunt and Mashhoudy, 2002]

References

[Barth, 1997] R. Barth. Metrics for effective information visualization. In Proceedings of the 1997 IEEE Symposium on Information Visualization (InfoVis '97), pages 0–108, DC, USA, October 1997. IEEE Computer Society Washington

[Hunt and Mashhoudy, 2002] Neville Hunt and Housh Mashhoudy, Discovering Important Statistical Concepts Using SpreadSheets. Created at: January 29, 2002. Retrieved at: October 28, 2006. http://home.ched.coventry.ac.uk/Volume/vol0/philosop.htm.