Data visualization is one of the key components in understanding data.
The Whiskers in Boxplot They are the outlier data points. Outliers are determined using the interquatile range (IQR, i.e., 25 percentile to 75 percentile.). We usually the lowest data point within 1.5 IQR range below the 25 percentile or the data point within 1.5 IQR range above the 75 percentile.
Histograms are good for understanding the distribution of your data. The Bin Size Problem As an example, we will use the following series as an example. [1.45,2.20,0.75,1.23,1.25,1.25,3.09,1.99,2.00,0.78,1.32,2.25,3.15,3.85,0.52,0.99,1.38,1.75,1.21,1.75] If we use bin size 1, we get this spiky chart and it is not so informing. We could also set bin size to 2. In principle, we could keep tuning the bin size until we get something pretty and informing. But that would be quite depressing.
Anscombe’s Quartet Anscombe’s quartet is a brilliant idea that shows the importance and convenience of visual representation of data. Anscombe’s quartet has four datasets. The values of each dataset are shown below. x1 = [10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5] y1 = [8.04, 6.95, 7.58, 8.81, 8.33, 9.96, 7.24, 4.26, 10.84, 4.82, 5.68] x2 = [10.0, 8.0, 13.0, 9.0, 11.0, 14.0, 6.0, 4.0, 12.0, 7.0, 5.
Basic Concepts of Colors Color Wheel and Color Sphere There are two dimensions in the color wheel: Hue Saturation When we add another dimension, lightness, to the wheel, we have a color sphere (1, 2). Many color systems have been invented. Color wheel and color sphere are two examples of them.
There are many principles of designing a visual representation of data. However, before we understand how data is represented visually, it would benefit us a lot if we understand the basic principles of designing on 2D surface. Robin’s CRAP Robin Williams proposed the four elements of design: Contrast Repetition Alignment Proximity Contrast Use some contrast to distinguish the elements of different contents. Repetition Repeat the design of similar elements on the same page and across pages to make sure the readers learn the meaning of the design quickly.