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Symbolizing top 10% of records, not values

August 25 2011 | 0 comments
Categories: Map Data

I am looking for a way to symbolize a score field which has values from 0 to 367004, with ~3000 records. I’d like just 4 categories. Graduated colors obviously. And am interested in the darkest color/last category showing the top 10% records. Meaning, for example, if the highest value is 367004 and the rest of the values are 20000 or less, I want that 10% category to have the top 10% of the records (the 367004 record plus the records with values 20000 or less which would be 10%, whatever it is), not to contain this one record. I hope I am wording this correctly!

Thanks for any help!

Mapping Center Answer:

On the Symbology tab for the layer properties, click Classify to open the Classification dialog box.  Here, you can specify 4 classes and select the Quantile method of classification which places equivalent number of records in each class.  You can then click the % button next the Break Values area and move the interactive break lines on the histogram or type them in at the right to ensure you get only the top 10% of records in your upper class. The Classifying numerical fields for graduated symbology help topic illustrates the dialog boxes involved.

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