Lab 4: Data Classification

For this week's lab, we created two maps on the senior population for Miami-Dade County, FL demonstrating four data classification methods: Equal Interval, Quantile, Standard Deviation, Natural Break. 

The Equal Interval method divides the total range by the total of classes desired by the map maker making an equal range of values. This method reveals outliers and conceals details of that data leading to misrepresentation because of the over simplification of grouping.

The Quantile method divides the data into classes with equal number of observations. It places the same amount of data values into each class and can be misleading because it can place some extremely different values into the same class. It can be useful for revealing patterns in linear data.

The Standard Deviation method places values in classes based on how they vary from the mean. It reveals how much the values are distributed around the mean and which groups are greater than average and less than the average. It conceals the actual values of the data.

The Natural Break method places values into natural groups within the data which makes it easy to see the variance between each of the classes. It can place outliers into one class which makes them easier to identify. However, if there is low variance in the data it can conceal the differences between each class and make it difficult to interpret. 

This first map shown below uses census data on the percentage of the population above 65 within each census tract. 

The second map is the population amount above 65 normalized by square mile. 

I think the natural break method best displays the data for an audience looking to target the senior citizen population because it is the easiest for the map viewer to decipher the distribution of senior population while maintaining sensible class ranges. The highest class does have a wide range especially compared to the equal interval method. I would still choose the natural break method over the equal interval method because many of the census tracts on the equal interval map appear to have the same percentage and amount of seniors, especially on the east side of the county however in the natural break map you can see that there is actually more of a variety. The natural break map is a more accurate representation of the senior population in the county.

If I were presenting data to the Miami Dade County Commissioners regarding the distribution of senior citizens, I would use the population count normalized by square miles method as it more accurately depicts the distribution. Having the data normalized by area gives the viewer a better understanding of where seniors are concentrated where as the percentage of seniors within a census tract gives no concept of the amount there are relative to the rest of the county. If the Miami Dade County Commissioners were using this data to decide how to allocate funding and resources to their senior populations, they would need to know the number of seniors in the census tracts in order to help the greatest number of seniors and not the percentage in each tract. For example, the 90.40 census tract has the highest percentage at 79% of seniors but there are only 95 seniors total. If the most amount of funding and resources were provided to this census tract, so many seniors in the county would be left out. The 58.902 census tract is the one with the highest number of seniors at 2372. If the largest amount of funding was provided to this tract, 2277 more seniors would benefit than if the percentage above 65 method was used to determine the distribution.