The first map, Number of People 2000, displays the number of people residing in each state according to the 2000 US Census. The values were calculated by the US Census Bureau and adapted visually. The color ramp works well for this data because there is no need for significant color changes. The values are simple and only need to show simple differences.
In the second map, Population Density 2000, the population per square mile is shown. The values were calculated by dividing the population by the area of the counties. This color ramp works well to highlight the changes in population density, as places of high population density such as southern California are extremely dark and distinct while places of lower population density such as North Dakota are extremely light.
The third map, Difference 1990 to 2000 Number of People, exhibits the differences in population from the 1990 census to the 2000 census. The values were attained by finding the difference between the two sets of data. The data from 1990 was subtracted from the 2000 data to find the difference in population. The color ramp works very well because it is easy to recognize the areas that increased in population from the areas that decreased in population since the ramp is divided in to two distinct colors.
The fourth map shows the percent change in the total population. The values were calculated by taking the values by dividing the population change value by the 2000 population value. The color ramp works well for the same reason that the third map's ramp works well, the two distinct colors make it easy to differentiate the areas that had a positive percent change in population and a negative percent change.
No comments:
Post a Comment