Key Terms Symbology Categorical attributes Style Layer file

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)

Review Questions 3. POP_2000 is a numeric field of the Cities feature class, which ranges from -99999 to 735617. 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

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

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

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

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.

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.

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

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

Quantitative Map 1: Graduated – Color Map

Quantitative Map 2: Graduated –Symbol Map

Quantitative Map 3: Proportional –Symbol Map

Quantitative Map 4: Dot Density Map

Quantitative Map 5: Chart Map

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

Standard Method 2: Equal Interval The entire range is equally divided by the number of classes you choose Example: range 1-1000, 5 classes: 1-200, 201-400, 401-600, 601-800, 801-1000. Useful for highlighting changes in the extremes and most appropriate for familiar data ranges, such as temperatures

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

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

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

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

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

EX 8a Standard Methods

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%)

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

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

Lab Assignment 4: Ex 8c

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