A radar chart is a graphical method of displaying multivariate data in the form of a two-dimensional chart of three or more quantitative variables represented on axes starting from the same point. The relative position and angle of the axes is typically uninformative, but various heuristics, such as algorithms that plot data as the maximal total area, can be applied to sort the variables (axes) into relative positions that reveal distinct correlations, trade-offs, and a multitude of other comparative measures.
The radar chart is also known as web chart, spider chart, spider graph, spider web chart, star chart, star plot, cobweb chart, irregular polygon, polar chart, or Kiviat diagram. It is equivalent to a parallel coordinates plot, with the axes arranged radially.
Now let's see the number of newborn babies who got a vaccine in each colony. Colony A has a total of 7 dots, which means that seven babies have been vaccinated. Similarly, colony B has three babies, colony C has five babies, and colony D has one baby who has been vaccinated. There are two types of dot plot: Wilkinson dot plot and Cleveland dot plot.
- Which observations are most similar, i.e., are there clusters of observations?and to locate similar points or dissimilar points. Are there outliers?
- Radar charts are used to examine the relative values for a single data point (e.g., point 3 is large for variables 2 and 4, small for variables 1, 3, 5, and 6)
- The dot plot shows the distribution of numerical variables where a value is represented by each dot on a number line or on graph.
- The distribution of continuous data points, such as a histogram, is shown in the Wilkinson dot diagram that displays individual data points rather than bins.
- The Cleveland dot plot shows graphical data elements and displays a continuous variable versus a categorical variable.
Radar charts are a useful way to display multivariate observations with an arbitrary number of variables. Each star represents a single observation. Typically, radar charts are generated in a multi-plot format with many stars on each page and each star representing one observation. The star plot was first used by Georg von Mayr in 1877.
Data Length of a Spoke
Radar charts differ from glyph plots in that all variables are used to construct the plotted star figure. There is no separation into foreground and background variables. Instead, the star-shaped figures are usually arranged in a rectangular array on the page. It is somewhat easier to see patterns in the data if the observations are arranged in some non-arbitrary order (if the variables are assigned to the rays of the star in some meaningful order).