Formulas are expressions that specify how the elements of an analysis depend upon one another. They are statements in an equation of facts, rules, principles, or other logical relationships. The ability of Scenario 360 to calculate values dynamically, using formulas, is a powerful and unique tool; it enables you to make changes in the analysis and see the results immediately.
Indicator formulas specify the value of indicators Indicators are the impact or performance measures that help people choose alternatives that best match their objectives or desired outcomes. An indicator is a calculated value that represents the impacts or outcomes of a scenario. Indicator results are automatically recalculated as you experiment with alternatives and the results can be displayed in a chart. Indicators apply to an entire scenario. An indicator might be used to evaluate costs, revenues, average household size, "community benefit", or total daily auto trips., which quantify information that pertains to a scenario as a whole. Example indicators include cost of roads, number of school-age children in a neighborhood, or town tax revenues. Indicator values are often charted in Scenario 360 analyses. Each indicator in an analysis is unique; that is, one indicator has one name and one value per scenario.
Attribute formulas specify the value of dynamic attributes A dynamic attribute is an attribute that is automatically updated as changes are made in the analysis. For example, a proposed road layer may contain dynamic attributes for length, pavement type, intersecting slopes, and construction costs. As each new road segment is added or modified, each of these dynamic attributes will be updated automatically. A formula is associated with each dynamic attribute that specifies how the attribute is calculated., which are changeable characteristics associated with particular features on the map. Example attributes include name of a road, number of children living in a house, or taxes for a particular lot. Attribute values are usually found by looking at symbols on a map or by clicking on a particular feature to open its attribute table.
For example, an attribute formula might be used to calculate the cost of each proposed road feature on a map (using a formula that multiplies the length of the road times the cost per square linear foot for that type of road). An indicator formula might be used to sum the total costs for all roads in a scenario (using a formula that adds the above attribute values).
On the edit formula tab (indicators and attributes) and in the Formula Editor, formulas are color-coded as follows:
Functions and operators are displayed with bold text.
Strings are displayed with dark blue text.
Targets, conversions, and layers are displayed with blue text.
Comments are displayed with green text.
Detailed information on working with formulas and functions can be found in the Working with formulas and functions in Scenario 360 document available on the Resource Disk that came with your Scenario 360 software.