Why do we use graphs?
“To make comparisons easier.”
Overuse of bubble charts. This chart show the world’s biggest banks and their capitalization from 2007 to 2009. The data shows how the capitalization has decreased over the two year period through the light and dark green areas of the bubbles.
The comparisons of the bubble chart and the bar chart shows how inaccurate bubble charts can be. Our brains think that the dark green bubble shows a 50% decrease but when the same data is shown in the form of a bar chart we can see how it actually about 1/3.
(Circle vs. Squares.)Squares are easier to compare than circles.
The use of colours and shading to represent heigh in a map is successful because there are more important things on the map that the reader needs to focus on. The bar graph in the top right shows data in a more accurate way, comparing the two data sets to clearly show the meaning extracted. On the scale, colours and shading is considered less accurate while position comparisons are more accurate (bar graphs etc).
Three most common charts.
- Time serious chart (left)
- Bar chart (middle)
- Scatter plot (right)
Bar charts are useful and easy to use and are widely known. It makes it quick to compare info especially when using numbers.
Line charts are as popular as bar charts, they conenct individual numeric data points. Simple way to visualise a sequence of values and to display trends over time.
Pie charts are used to show the relative proportions of information.
Different graphs are used to show different types of information and data, if used incorrectly the information becomes blurred to the viewer.