Go up
From the Help Desk - Legend Classification Methods
Posted on Sep 27, 2019 by Admin
Hello readers! This week we provide an in-depth response to a question asking about the legend classification methods in SimplyAnalytics. This response is now part of our Help Center: https://simplyanalytics.zendesk.com/hc/en-us
Question: Can you explain the legend classification methods?
The classification method controls how the data in your map is grouped. Areas on the map are assigned to groups using different classification methods. The colors you see on the map depend on which class is assigned to each area.
There are multiple methods for calculating break points for the data. You can select any of the following from the Classification Method menu:
- Quantiles (Local)
- Quantiles (National)
- Natural Breaks (Local)
- Natural Breaks (National)
- Equal Intervals
- Custom
Quantiles (National): This is the default method used to classify each area on the map, and works for most situations. Breakpoints are calculated so that each category contains about the same number of features. "National" uses a sample of locations from throughout the USA to calculate the breakpoints.
Example: If there are 35,000 ZIP Codes nationally and you have 5 categories the legend is calculated so there are theoretically 7,000 ZIPs in each category.
Quantile classes are easiest to understand, but they can be misleading if the data being mapped is not distributed normally. For example, population counts are usually not suitable for quantile classification because only a few places are highly populated. Use population density or percentages for more meaningful maps.
Quantiles (Local): Breakpoints are calculated so that each category contains about the same number of features. "Local" uses a sample of locations from your current view to calculate the breakpoints. This method usually ensures the map will show more colors. For example, if there are 50 ZIP codes visible on your map, and you choose to display them in five classes, the map will show 10 ZIP codes per color.
Natural Breaks (National): Breakpoints are calculated using a statistical formula that finds groupings and patterns in the data. "National" uses a sample of locations from throughout the USA to calculate the breakpoints.
Natural Breaks (Local): Breakpoints are calculated using a statistical formula that finds groupings and patterns in the data. "Local" uses a sample of locations from your current view to calculate the breakpoints.
Equal Intervals: This method uses equal-size intervals for each class and color on the map. Breakpoints are calculated so that each category has the same range. This method doesn't care if all areas on the map end up sharing the same color.
Example: if the lowest value nationwide is 1 and the highest value is 100 for that specific geography the legend will have 5 equal categories 1 to 20, 21 - 40, 41 - 60, 61 to 80 and 81 to 100
Custom: The user selects their own breakpoints by typing in their own values.To set your own custom breakpoints, you can click in each value’s cell and enter a value of your choice. You can also click the colors to customize how the map looks.
More information on data classification/reference:
https://gisgeography.com/choropleth-maps-data-classification/
More from SimplyAnalytics
Posted on Mar 09, 2010 by Admin
The GRI team will be exhibiting at the 2010 Public Library Association conference later this month at the Oregon Convention Center in Portland, OR. The PLA National Conference is the prem...
Posted on May 28, 2009 by Admin
The Charleston Advisor, which publishes critical reviews of online resources for libraries, published a review of SimplyMap in April. We are very pleased to have received 4 1/4 stars out...
Posted on Aug 13, 2015 by Admin
In this quick SimplyMap report, we use Census data to help us identify which city in the United States has the highest percentage of residents who reported walking to work as their mode o...
Posted on Mar 02, 2018 by Admin
In this week’s blog we’ll take a look at how to enter an address in SimplyAnalytics to find the Census Block Group or Census Tract. Let’s get started! Use Case: You want to analyze the ar...
Posted on Jun 02, 2017 by Admin
We will be exhibiting at SLA in Phoenix, AZ on June 18th-20th. You can find the SimplyAnalytics team at Booth #905. Stop by and check out our groundbreaking new interface, have a chocolat...
Posted on Dec 15, 2014 by Admin
Visit the SimplyMap team at the ALA Midwinter Meeting in Chicago late January. We will be at booth #2824 offering product demonstrations, tips & tricks, and of course Ghirardelli Choc...
Posted on Jun 09, 2016 by Admin
In this week’s blog, we’ll be featuring our newest data offering, PRIZM® Premier. If your institution currently subscribes to PRIZM data, this new module is available at no additional cos...
Posted on Aug 02, 2016 by Admin
Did you know that you can use SimplyMap to identify which make and model of vehicle is most prevalent within any location in the United States? In this week’s SimplyMap report, we’ll take...
Posted on Nov 22, 2016 by Admin
We will be exhibiting at ALA Midwinter in Atlanta, Georgia in January. You can find the GRI team at Booth 1155, where we will be catching up with customers old and new, and sharing some e...
Posted on Jul 24, 2013 by Admin
Registration is now open for the North Carolina Library Association Conference! Visit us at the 60th biennial conference (Booth #45) through October 15 - 18, 2013. We have beautiful ca...