1. Key Terms
Symbology
Categorical attributes
Style
Layer file

2. Review Questions
POP-RANGE is a string field of the Cities feature class with the following entries: 0-9,999, 10,000-49,999, 50,000-99,000…This is an example of categorical/qualitative/descriptive attribute. True/False?
You can symbolize the Cities features above by selecting POP-RANGE in the Value Field list under Properties\Symbology/Categories (first right-click the Cities feature class in the Table of Content)

3. Review Questions
3. POP_2000 is a numeric field of the Cities feature class, which ranges from to This is an example of quantitative data. True/False
4. A layer file with an extension of .lyr can have different name from its source data. True/False

4. Lect 4 Classifying Features
Classifying features by standard methods
Mapping density
Using graduated and chart symbols

5. Quantitative Maps
Show numeric values in relation to one another on a continuous scale
Group or classify these values to separate data visually and understand data easily
Examples: population of a county, area of a city block, length of a water distribution line

6. Quantitative Map 1: Graduated – Color Map
Graduated – color map: uses a change in color to represent data classification
Color ramp
Light color for small values, dark color for larger values

7. Quantitative Map 2: Graduated –Symbol Map
Graduated-symbol map uses a symbol that varies in size to represent numeric attributes values
Generally 3 to 7 graduated colors used
Example: Points that increase in size can present a city’s growing population.

8. Quantitative Map 3: Proportional –Symbol Map
Similar to a graduated-symbol map, except that the symbols are drawn proportionally in size
These symbols are most appropriate for data that has a relatively narrow range of values
Example: A county with a population of five million people would have a symbol five times larger than a county with a population of 1 million people.

9. Quantitative Map 4: Dot Density Map
Represents quantities using randomly placed dots to form a density pattern inside a polygon
Each dot is equal to a predetermined attribute value
The more dots, the greater is the value of the polygon

10. Quantitative Map 5: Chart Map
Used to represent multiple attributes for a single feature
Pie, bar, stacked charts
Charts that can be similar in size or vary based on proportionality

11. Quantitative Map 1: Graduated – Color Map

12. Quantitative Map 2: Graduated –Symbol Map

13. Quantitative Map 3: Proportional –Symbol Map

14. Quantitative Map 4: Dot Density Map

15. Quantitative Map 5: Chart Map

16. Standard Method 1: Manual
Set class breaks manually
By typing them
Or by adjusting the histogram break bars in ArcMap

17. Standard Method 2: Equal Interval
The entire range is equally divided by the number of classes you choose
Example: range , 5 classes: 1-200, , , ,
Useful for highlighting changes in the extremes and most appropriate for familiar data ranges, such as temperatures

18. Standard Method 3: Defined Interval
Similar to an equal interval
But you get to define the interval size to determine how many classes there are
Example: range of test score from 50 to 90, interval size is 10: 50-60, 61-70,71-80, 81-90

19. Standard Method 4: Quantile
All classes have the same number of features
Best for those linearly distributed data
Create a balanced-looking map: no classes have too many, too few or no values

20. Standard Method 5: Natural Breaks (Jenks)
Based on natural groupings inherent in the data
Boundaries are set where there are relatively large gaps between values
Best for unevenly distributed data, such as population

21. Standard Method 6: Geometrical Interval
Class breaks based on class intervals that have a geometrical series, such as a logarithmic distribution.
Best for continuous data with dramatic range

22. Standard Method 7: Standard Deviation
Best for normally distributed data (Bell-shaped curve)
Create classes based on a specified number of standard deviation from the mean value
A divergent color scheme is recommended

23. EX 8a Standard Methods

24. Histogram: Frequency Distribution Chart
X-axis: range of values in the BURG02 field
Y-axis: count of features
Vertical blue lines: class breaks
Gray columns: number of features that fall within a specific span of the total range of values (100 columns drawn, each column represents 1%)

25. Ex 8b Mapping Density Area units, dot size, dot value, dot placement
Random distribution of dots can be misleading: e.g., the majority of the population is centered on urban areas
Experiment until producing good results: usually choose medium-size dots

26. Ex 8c
Lab assignment 4:
Complete Ex 8c
Display the map in Layout View as shown on Page 297
Export the map as PDF
it to the instructor

27. Lab Assignment 4: Ex 8c

28. Key Terms Graduated – color map Graduated – symbol map
Proportional –symbol map
Dot density map
Manual Classification
Histogram
Defined interval
Quantile
Natural Breaks
Standard deviation