The IRPE only indicates the improvement degree of performance
estimation. However, determining the importance rating
of achieving the ITPE of a CR must take the IRPE of this CR into account,
and must simultaneously consider the total effort of achieving
the ITPE of this CR, the total feasibility of achieving the ITPE of
this CR and the proper Kano categories that this CR can be grouped
into. Because the IRPE is not the exclusive decisive factor for determining
the importance rating of achieving the ITPE, the other decisive
factors such as the resources and organizational ability must
be taken into account. Therefore, the concept of the importance
rating of achieving the ITPE of a CR is introduced as following.