Logical Decisions - Classweb

decision maker to state importance as a percentage of the first
member's one hundred point swing weight. If the decision maker
thought that swinging a member was half as important as
swinging the first member she would give it a swing weight of
fifty.
You can continue in this way until the decision maker has
assigned a swing weight to all of the members.
The idea of the relative importances of swinging members
through their ranges is rather abstract. However, studies and
experience have shown that decision makers are willing to
provide this information and often feel very comfortable doing so.
To compute the absolute weights for the members from their
swing weights, LDW simply adjusts the swing weights so they
sum to one.
The other two importance ratio methods -- pairwise weight ratios
and the analytic hierarchy process -- ask the decision maker to
specify ratios between pairs of members.
In the pairwise weight ratios method, LDW helps you identify
pairs of members for which to define weight ratios. When you
have entered enough ratios to define a complete set of weights,
the process is complete.
To compute a complete set of weights, you must define ratios that
include each active member at least once. This means that if there
are n active members, you need to enter n - 1 ratios. LDW uses
this information and any information on interactions to compute
the absolute weight for each active member.
The Analytic Hierarchy Process is like the pairwise weight ratios
method. However, instead of entering ratios for selected pairs of
members, you enter ratios for all possible pairs. This means that if
there are n active members, you need to enter n*(n - 1)/2
importance ratios. Since this is more than the minimum needed
to compute the weights (n - 1), there may be inconsistencies in
your answers. See page 9-30 for a discussion of the consistency
measures used in the AHP method.
The weight for each active member is computed using a matrix
algebra approach that is generally very close to the geometric
mean of the ratios in its matrix row. The geometric mean is the
9-40 Section 9 -- In Depth