Rapporto Tecnico, Anno 8, n.48; Novembre 2013

7.3.3 Radar chart
These graphs show all the variables in semi-axes or radii which radiate from the centre of the log. Each
radius represents a variable, and they are graduated to show levels and thresholds in linear or logarithmic
scale. The value of each variable is marked in its radius (the centre is the value 0 for all variables). All the
marks are linked by segments, resulting in an irregular star-shape polygon called radar chart.
This graph helps to study globally the risks, showing their features, trends and relations between risks.
Once the risks are calculated, to get the chart the first step is drawing the centre and radii. Scales are drawn
in the radii, drawing a circle (or regular polygon) with all the radii inside it. It is important that the angles
between consecutive semi-axes are always the same. Sometimes circles or polygons are drawn representing
minimum or maximum thresholds.
These diagrams are useful to show graphically balance or unbalance in the axes, to show maximum and
minimum profiles and to show evolution.

Figure 8: example of radar chart

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