Bivariate map
Encyclopedia
A bivariate map displays two variables
on a single map
by combining two different sets of graphic symbols or colors. Bivariate mapping is an important technique in cartography
. Given a set of geographic features, a bivariate map displays two variables
on a single map by combining two different sets of graphic symbols. It is a variation of simple choropleth map
that portrays two separate phenomena simultaneously. The main objective of a bivariate map is to find a simple method for accurately and graphically illustrating the relationship
between two spatially distributed variables. A bivariate map has potential to reveal relationships between variables more effectively than a side-by-side comparison of the corresponding univariate maps.
A bivariate map is recent graphical method which is intended to convey the spatial distribution of two variables and the geographical concentration of their relationship. A bivariate choropleth map uses color to solve a problem of representation in four dimensions; two spatial dimensions — longitude and latitude — and two statistical variables. Data classification and graphic representation of the classified data are two important processes involved in constructing a bivariate map. The number of classes should be possible to deal with by the reader. A rectangular legend box is divided into smaller boxes where each box represents a unique relationship of the variables.
In general, bivariate maps are one of the alternatives to the simple univariate choropleth map
s, although they are sometimes extremely difficult to understand the distribution of a single variable. Because conventional bivariate maps use two arbitrarily assigned color schemes and generate random color combinations for overlapping sections and users have to refer to the arbitrary legend all the time. Therefore, a very prominent and clear legend is needed so that both the distribution of single variable and the relationship between the two variables could be shown on the bivariate map.
Variable (mathematics)
In mathematics, a variable is a value that may change within the scope of a given problem or set of operations. In contrast, a constant is a value that remains unchanged, though often unknown or undetermined. The concepts of constants and variables are fundamental to many areas of mathematics and...
on a single map
Map
A map is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes....
by combining two different sets of graphic symbols or colors. Bivariate mapping is an important technique in cartography
Cartography
Cartography is the study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively.The fundamental problems of traditional cartography are to:*Set the map's...
. Given a set of geographic features, a bivariate map displays two variables
Variable (mathematics)
In mathematics, a variable is a value that may change within the scope of a given problem or set of operations. In contrast, a constant is a value that remains unchanged, though often unknown or undetermined. The concepts of constants and variables are fundamental to many areas of mathematics and...
on a single map by combining two different sets of graphic symbols. It is a variation of simple choropleth map
Choropleth map
A choropleth map A choropleth map A choropleth map (Greek χώρος + πληθαίν:, ("area/region" + "multiply") is a thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map, such as population density or per-capita...
that portrays two separate phenomena simultaneously. The main objective of a bivariate map is to find a simple method for accurately and graphically illustrating the relationship
Relationship
Relationship or relationships may refer to:* Interpersonal relationship* Intimate relationship* In mathematics and statistics:** Binary relation** Causal relationship** Correlation and dependence** Direct relationship** Inverse relationship...
between two spatially distributed variables. A bivariate map has potential to reveal relationships between variables more effectively than a side-by-side comparison of the corresponding univariate maps.
A bivariate map is recent graphical method which is intended to convey the spatial distribution of two variables and the geographical concentration of their relationship. A bivariate choropleth map uses color to solve a problem of representation in four dimensions; two spatial dimensions — longitude and latitude — and two statistical variables. Data classification and graphic representation of the classified data are two important processes involved in constructing a bivariate map. The number of classes should be possible to deal with by the reader. A rectangular legend box is divided into smaller boxes where each box represents a unique relationship of the variables.
In general, bivariate maps are one of the alternatives to the simple univariate choropleth map
Choropleth map
A choropleth map A choropleth map A choropleth map (Greek χώρος + πληθαίν:, ("area/region" + "multiply") is a thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map, such as population density or per-capita...
s, although they are sometimes extremely difficult to understand the distribution of a single variable. Because conventional bivariate maps use two arbitrarily assigned color schemes and generate random color combinations for overlapping sections and users have to refer to the arbitrary legend all the time. Therefore, a very prominent and clear legend is needed so that both the distribution of single variable and the relationship between the two variables could be shown on the bivariate map.