Each of these resources can be used individually to draw attention to map features, or they may be used in combination. Sometimes cartographers deploy several of these resources simultaneously to stress particularly important information or to improve its legibility. 5.2 Strategies of symbolization With such a range of resources available, the question arises as to what strategies to use in assigning these resources to points, lines, and areas. The strategies employed vary greatly depending on the nature of the phenomena being mapped. Points Areas Lines Interval data is information that can be arranged using a standard scale along which operations of addition and subtraction have meaning.
Temperature is an example of an interval measure.
Ratio data is information that, like interval data, can be arranged along a scale but, in addition, the scale begins at a non-arbitrary zero point. At the zero point, no features are present. The operations of multiplication and division can be employed with ratio data to consider proportions and magnitudes. Elevation above sea level, precipitation, and population are all examples of ratio data. These resources can be used in a wide variety of ways and several may be used at once to highlight or reinforce a single relationship.