Choropleth Maps are thematic maps based on predefined
aerial units. Think of it as a multi-colored checkerboard map.
Some maps, (ex. road maps), show many types of data while thematic
maps are made to show only one specific set of data. Because each
group of data is organized as a ratio value, (a zero value for comparison
is present), we use what a graded color series to show least intensity
to most intense (shown using a light to dark color pattern). Using
the colors of the rainbow is not a good idea for making a graded color
scheme. I would look at the red shaded areas and assume they are
showing the most intensity, but somebody else may assume that violet is
most intense. The rainbow color scheme works better for nominal
data. This would be a choropleth map showing the various religions
preferences by zip code or the car models most prevalent on a state by
state basis. Nominal maps are based on name features of places.
The following three maps were created using the FactFinder feature
Census Website. I was not able to get the map to show all the
northern edge of Florida without cutting out the majority of the state.
If you use this program to create your own maps, you will see that it is
not an easy process. I got frustrated different times when things
did not work how I wanted. With more practice (and a faster internet
connection), the process would become easier.
|This is the first map that I created. This choropleth map shows
the Percent of People who are Hispanic per county in Florida based on Census
data from 2000. The data is divided up into 5 natural breaks.
That means the groups are divided into unequally sized groups that attempt
to group like data together. The program did this for me, but a map
maker can do this by hand if no computer program is available. Looking
at the legend, you can see where it skipped intervals where no data applied
(ex. between 3.9 and 4.1%). This is one way to show the data, but
is not the only correct way.
|This map is also showing the Percent of People who are Hispanic per
county in Florida. The map looks remarkably different since there
are fewer counties showing up in the highest data class. I choose
to change the legend to five equal intervals. Here the data
groups are not distributed according to natural grouping but rather equal
intervals, about 11% in this case. In Map 1, the 1st group goes from
1.5 to 3.9, but in Map 2 (above), the first group goes from 1.5 to 12.7.
|Here in my third map, I chose to show some of the additional features
of the FactFinder website. The data is divided into four quartiles
according to the program. Quartiles divide the data into a certain
number of groups (in the Map 3 there are four quartiles but any number
will work), where each group has the same number of counties (if there
were 124 counties in the state and you used quintiles, or 4 quartiles,
then each group would include 31 counties). This map is deceiving
since we are missing part of north Florida where less Hispanic people live.
You can see that Miami (Dade County) area is in the bright red 9.5 to 57.3%
Hispanic area. I also had this map show major roads, railroads, and
jails, but as you can see, the railroads and jails did not show up zoomed
out this far. I also changed the color to an orange scale.
The red counties tended to cover up the major roads, so in the future,
I would not use this color if I were going to show the major roads.
The next four maps were done using a different program located at the
for International earth Science Information Network website.
I used the DD Viewer version 2, but they also have a newer version 3 to
use free of charge. I found this to be a much easier program to use
than the FactFinder program I used to make the maps above.
|For this series of maps, I choose to look at the opposite end of the
nation. I choose to make some choropleth maps detailing the % Black
Condo Owners in California. I hoped that this would show me where
the affluent minorities live. This doesn't take into the fact those
minorities living in large houses or mansions. Here, as the title
indicates, I have used the 4 quartiles (or quintiles) method
to show my data. I used the default yellow to red graded color
|In the second map of the series, Map 5, I switched to a 4 equal
steps division system. This means that each group is an equal
number. In this case, every group is 5%. As above in Map 2,
we notice very few counties made it into the largest percentile bracket.
I doubt that this is the case for all maps, it just happened that both
of the themes I chose were minorities. If I had looked at
the Percent of People who are Caucasian, then the majority of the counties
would have been the darker color.
|Here I wanted to make my own graded series. I think it turned
out well although it would be easier to see if the background was white
instead of black.
|Instead of choosing my own graded series, I used the feature on the
Ceisen website where it helps you create your graded color series.
I picked a creamy pink color to be the starting point of the series and
a dark maroon to be the ending point and let the computer pick the middle
two colors for me. I like how this one turned out. The only
complaint is the light color may appear to white making it look like I
had no data for those counties.