Time and Relative Measurement
As virtually any
accountant or finance manager knows, the need to present results in reference
to time is important. It is hard to imagine a cube without a time
dimension (although I have seen it, it is rare, indeed), because time is
a pervasive concept in analysis. Business is measured by activity and activity
is based heavily upon the concept of time. Because we measure virtually
everything at a point in time (such as an asset, or other balance,
within a balance sheet), or over a period of time (such as revenues
within an income statement), time becomes a consideration that relates with
most other common dimensions we see in cubes.
Time also serves as the
foundation that underlies another important concept, growth.
Growth of course, can be a positive or negative quantity, the desirability of
which is dictated by the dimension and measure intersects that are posed in a
given scenario. Revenues, production volumes, returns on equity and other
measures are commonly seen to be good candidates for growth, especially when
that growth is happening within the scope of our own interests. Likewise,
decreases, shrinkage and other antonyms of growth can be equally delightful
news, when announced within the context of overhead expenses, operating costs,
tax liabilities, customer complaints and many others. To have meaning, growth
and its opposites must have referential context, and often the more "comparability"
we can obtain, the better. It is thus vital to be able to ascertain the change
in measures over time. Second in importance only to the positive / negative nature
of those changes are the tandem considerations of "how much" and "how
rapidly."
The cyclical nature of
business (more in some industries than others, of course) is another compelling
reason to be able to provide period-based analysis. As is somewhat obvious, a
cyclical business will obtain more useful "period over period"
analysis if they are able to compare "apples and apples." An example
might be the sales of those frivolous, transitory items that seem to appear in
advertising only around the Christmas season; things one would purchase as a
gift to in-laws, if at all, such as "hotdog toasters" and the like. Month-to-month
comparisons of revenues / units sold information for these products would not
be scrutinized as heavily as, say, November and December sales for the most
recent year compared to the sales of the same months in the previous year.
MSAS provides excellent
tools for presenting data within the relative time concepts so valued by
information consumers. The implements it offers us in this arena include:
-
Time
dimension(s)
-
Alternate
hierarchy capabilities
-
MDX
time-series functions
-
Calculated
members.
NOTE: For detailed information on time-series
functions, see the following Database Journal articles in my MDX Essentials series:
This article, as well as
subsequent articles in this series, will treat the practical presentation of
data with time as a consideration. While the specialized time-series functions
are called upon, we will look at a combination of MDX elements to bring about
the results we are called upon to obtain, explaining each within a multi-step
practice exercise.
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