Hello, fellow Cartographers!
This week's lab was definitely an interesting one as we got to explore different methods of data classification using census data from Miami-Dade County. We were expected to properly demonstrate the four common data classification methods: Natural Breaks, Equal Interval, Quantile, and Standard Deviation. When it came to presenting the data in layouts, we had to prepare a map with four data frames, symbolize the map for intuitive data acquisition, be able to properly implement cartographic design principles into our final maps, and then compare and contrast the classification methods that were used to find the best representation of spatial data for the specified audience (Miami-Dade County Commissioners). Not only did we have to do this once, but twice! We were also tasked with using the same classification methods but normalizing the data this time around and using a different field. In the first set, we analyzed the percent of the population age 65+ in census tracts, for the second set we analyzed actual population counts age 65+ but by normalizing the data into square mile regions. Once we completed that analysis, we had to compare and contrast the two map sets to decide which is the best data presentation method, and also identify which method is the best suited to present distribution data.
Now that you understand what the objective of this lab is, I will explain my maps and go into more detail about the different classification methods.
The first map I am about to show you is the percentage of the population 65+:

In the first square (top left) I am demonstrating the Natural Breaks classification. In case you don't know how Natural Breaks works, it takes numerical values of ranked data are examined to account for non-uniform distributions. This then results in unequal class width that has a varying frequency of data observations for each class. The second square (top right) is Equal Interval classification, which is the data range of each class being presented is held constant. This in turn gives an equal class width with a varying frequency of observations for each class. The third square (bottom left) is Quantile classification, this is when data observations are distributed equally across the class interval. This then results in unequal class widths but the same frequency of data observations for each class. The fourth square (bottom right) is Standard Deviation classification, this method is for normally distributed data. This means that class widths are defined using standard deviations from the mean of the data array. This then results in giving equal class widths and a varying frequency of data observations for each class. Looking at this map, in my opinion, the best classification method for displaying the percentage of the population 65+ is the Quantile classification method. I believe this because it equally distributes the data over the county and I believe it best displays the data by clearly showing where the more centralized areas of the senior citizen population are located.
For my second map, I used the same classification methods but used a different field to present the data. This time instead of a percentage, I used actual population counts of individuals age 65+. Unlike before, I normalized the data by census tract areas which are measured in square miles. Just in case you don't know what normalization is, it is the process of taking a count (population count) and dividing it by something else (square miles) to make a number more comparable or to put it in context. Here is how my map turned out:
You can tell that this map is very different compared to the first map. In another part of this assignment, we had to figure out which data presentation method would be best to present to the Miami-Dade County commisssioners regarding the distribution of senior citizens, and by looking at the second map it is clear which one is the better option. I believe that the population count normalized by area more accurately depicts the distribution. My reasoning for this is that the population count normalized actually counts every individual living in that area. The reason why percent above 65 doesn’t really work is because percentage growth doesn’t really represent the number of actual people living in an area. Think like this, if a census tract had around 100 people age 65+ in 2010, when the next census tract comes around the population has grown to 175 people. That is a 75% increase in the 65+ population, that may look good and all but it doesn’t mean a lot of people within that demographic live there. With that reasoning, using the population count normalized by area is the best way to present data to the Miami-Dade County Commissioners.
After completing this lab, I am looking forward to figuring out ways I can utilize these different classification methods for my full-time job. Thanks for reading!