Blog # 2

Choropleth Map


          
      Choropleth maps are used when data is categorized into counties , countries, or provinces, when data is standardized to show rates, as well as if there is a continuous statistical surface. These form o maps use differences in shading, coloring, or the placement of symbols in predefined areas to indicate the values in those particular areas. Choropleth maps are also used to group data into 2 or more levels or classes using slicing values . Although choropleth maps are commonly used they make it easy for data to be slanted , maps like such also create the illusion of rapid breaks whereas data varies continuously and gradually in the real world. Choropleth maps also allow small areas to overwhelm the data of large regions. 

Isarithmic Map 



         Isarithmic maps depict continuous and smooth phenomenons , a common example are weather maps as shown above. Isometric maps uses isolines, which are lines that connect equal values to illustrate continuous data such a elevation, air pressure, and precipitation. Data issues with isarithmic  maps is that data is derived from point data which can take two forms; true and conceptual. With true point data, points exist where measurements were taken . With conceptual point data, points exist at the centroids of enumeration units. Isometric maps can represent raw or standardized data .

Dot Density Maps

       Dot density maps are effective ways to show density differences in geographic distributions across a landscape.  Dot density maps are also easy to understand, requiring little cognitive effort by the map reader when compared to isoline maps. However, retrieval of specific information from dot density maps is difficult, as map users find manual counting of dots tedious and tend to underestimate dot totals as density increases. There are two kinds of dot density maps: one-to-one maps and one-to-many maps. For one-to-one dot density maps, each point on the map corresponds to a single incidence of the mapped phenomenon. One-to-one dot density maps are general-reference maps, symbolizing spatial location only. Because of this, care should be taken to ensure that the dot is accurately located on the map.

Proportional Symbol Map 

         Proportional symbol map scale the size of simple symbols , which are usually a circular or a square shape. These forms of maps are usually easy to grasp , the larger the symbol or shape is the more that particular item exist in that particular area. These forms of maps are very flexible , and easier for individuals to extract the numerical data. 

Environmental Sensitivity Index Maps 

      These forms of maps provide a summary of coastal resources that are at risk if environmental disasters occur such as oil spills. When disasters like these take place these forms of maps assist responders in reducing the environmental consequences of the disaster and the clean-up efforts. These forms of maps can also be used to plan for disasters in vulnerable and more susceptible locations. By utilizing these maps as a preventive measure , users are able to identify possible disaster locations, wild-life and humans who may be affected and need to be protected , and strategies for how they can be fixed.