Sunday, February 26, 2017

Modeul 6: Data Classification

During this lab I applied four different classification methods (Equal Interval, Quantile, Standard Deviation, and Natural Breaks) to U.S. Census data for Miami Dade County, Florida. I created two maps displaying senior population by tract in Miami Dade, each with different presentation methods, using four data frames for the four classification methods listed above. The first presentation method was mapping percentage of people 65 and older compared to the total populations of each tract, and the second method was displaying the number of people 65 and older normalized by square mile in each tract.

After creating these maps, I compared and contrasted the classification methods to determine which was best suited to represent the spatial data for a specified audience as well as the presentation methods to determine which was best suited to present the distribution of data. I determined that the natural breaks classification method would be the most useful for an audience targeting senior citizens because it revealed useful patterns in the data such as potential extremes and differences between values while also maximizing variance of inter-class values and minimizing variance of in-class values. Although this method does not consider how values are distributed on a number line, I think the natural breaks still did a decent job of maintaining the distribution of seniors as displayed by the other methods. I determined that the normalized presentation method (shown below) does a better job at representing the distribution of seniors in the county because the percentage-based method causes some tracts to be placed in the highest class, while they actually only have a high relative proportion of seniors compared to the total population in that region. Although I think knowing the distribution of percentage of people 65 and up compared to the total population could be useful in conjunction with the other presentation method, it alone does not help the audience gain an understanding about how many seniors actually live in the area.


The map above is the map I created using the four methods of classification and the normalized presentation method. It shows 2010 U.S. Census data by tract normalized by square mile using four different classification methods. In addition to the natural breaks method described above, I used the equal interval method, where the range of all classes are the same. The quantile method places an equal number of values into each class, and the standard deviation method contains classes that include values within a certain standard deviation of the mean and is best for displaying data with normal distributions. This lab helped me gain a thorough understanding of the various classification methods, when each one is appropriate, and how important it is to choose the best one so that viewers have a useful map they can rely on to make important decisions.

1 comment:

  1. Now Callie you will have to interpret that for me, It's a little over my head.

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