Understanding Duration Aliases

The system calculates a duration by subtracting an earlier date from a later date. The remainder is the duration.

A duration alias measures the length of a period of time. The most common durations are ages. An employee's age on a particular date is the duration between that date and the birth date. Another common duration is elapsed time service, the period of time between two service-related events, such as a hire and a termination.

Setting up a duration alias is a two-part process. You need to:

• Specify the endpoints for the duration—for example, birth date and event date.

• Select a calculation method.

You define calculation methods on the Calculation Options and Conversion Options pages.

Duration aliases always produce decimal results. For example, a duration of six years and three months is expressed as 6.25 years. When you create a duration option you establish a method for converting raw dates—formatted in years, months, and days—into decimal equivalents.

The decimal that represents the total duration is the primary result of a duration alias. However, duration aliases also manipulate the decimal value to derive six other secondary results.