Attribute data

1. In a vector setting Stored in a relational database for each geographic object A relational database is organized in a series of two-dimensional tables, each of which contains records for one data object. A �row� of data for each point, line, or polygon Attribute data

2. Vector setting: attribute data:

3. Raster setting: attribute data In a raster setting Stored as a grid of cells (each cell is given one number)

4. Raster attributes: cell values

5. Attribute data Three types of data: Nominal scale Ordinal level Interval and ratio levels

6. Attribute data types Nominal data � descriptors about the objects � numbers do not quantify an amount

7. Ratio data: ratios make sense (3:1) for these data(which means that �0� means �nothing�/�none�/�zilch�) mm of precipitation Resident population Elevation (contour lines: 30m, 40m, 50m, etc.) Average household income (of census tract) Age

8. Interval scale: adding numbers are meaningful, but ratios aren�t Fahrenheit Celsius Note: 10 degrees cooler means the same thing at each temperature. But 20 degrees doesn�t mean twice as much as 10 degrees. Also, 0 degrees doesn�t mean �no degrees�.

9. Ordinal data Numbers identify an order only (no scale) Road size:, 1-forest path, 2-dirt road, 3-gravel road, 4-country road, 5-major highway 1-never, 2-sometimes, 3-often, 4-always 1-sober, 2-tipsy, 3-drunk, 4-smashed/pissed (British), 5-plastered 1-small, 2-medium, 3-large