For instance, if there are 250 employees in the
organization, we expect at least one record for each one of them to be in the
database.
??? Timeliness:.It measures the delay between a change in the state of the real
world and the corresponding data warehouse update. This dimension is tightly
associated with other two: currency and volatility. Timeliness is affected by
three main factors: (a) speed at which the state of the information system is
updated after the changes occur in the real world; (b) frequency of change of
the state of the real world; and (c) the instant when the data are actually used.
The first aspect depends on the design of the system, while aspects (b) and (c)
are design-independent.
??? Currency: Measures the age of the data. It is computed as follows (Wang &
Reddy, 1992)"
Currency(d) = tc ??“ t0
Where d is the data element under consideration, tc is the present time, and t0
is the instant in the real world when the data element was created. An alternative
definition is:
Currency(d)= tf + (tl + te + tq)
0 Vaisman
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tf = time in the data source: the time elapsed between the instant when the data
were ???born??? in the real world and stored in the data source, and the moment
when they are transferred to the data warehouse.
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