Module 6 - Data Classification

In this week's lab, we learned about different methods of data classification and when each is used to best represent data. One major objective for this week was to learn how to use ArcGIS (ArcMap) to create maps using these classification techniques, and to compare and contrast the various techniques. The most difficult part of this assignment for me was determining when a specific classification technique is better than another for a particular set of data, but I think a lot of that probably comes from experience.

The map below shows the percentage of people over age 65 in Escambia County using four classification methods: natural breaks, equal interval, quantile, and standard deviation. The entirety of this lab was done using ArcMap. I was able to get all 4 data frames on one map here with some helpful hints from the online lecture video. Getting all 4 frames on one map is very useful for comparing and contrasting the different techniques. I found the process of creating the different symbologies very easy to do ... the hardest part for me was deciding what color scheme represented the data the best.

I think all the methods do a reasonably good job of representing this particular set of data well. I like the standard deviation and the equal interval methods the best here. The standard deviation method clearly shows where the lowest and highest percentages of people over 65 are (they are more than 2.5 standard deviations from the mean in either direction). I know I have to be careful using this method however, as it only is effective with normally distributed data. If I want to know the numbers, I like the look of the equal interval method in this case. I think it shows the minimum and maximum values the best when compared to the surrounding census tracts, and is easy for the user to interpret.