Software Engineering

14.1.3 
Establish the success criteria
The success criteria must be established, against which candidate alternatives will 
be assessed. Success criteria establish the minimally acceptable and objective fac-
tors that characterize the ideal solution. This provides a range of values for each 
success factor within which an alternative should be deemed acceptable. The alter-
native that is determined to be best suited to be adopted into the software architec-
ture should conform to a majority of the success criteria.
Success criteria must address an assortment of software life-cycle factors, 
including performance, technical difficulty to implement, usability, effect on the 
enduring properties of the software architecture, and risks to project success. These 
criteria should be weighted to prove a balanced appraisal of an alternative. The suc-
cess criteria and weighting scheme should ensure that all success factors influence 
the determination of the preferred solution.
A radar or spider chart provides a diagrammatic means of expressing the success 
criteria and rating the alternatives. A radar chart is a graphical method of displaying 
multivariate data in the form of a two-dimensional plot of three or more quantitative 
variables. Each variable or success factor is measured on an axis that extends from 
a center point similar to a spoke on a wheel. The innermost ring of values represents 
the minimal value for each success factor and the outermost ring of values represents 
the objective values. When an alternative’s measurement falls below the innermost 
ring, touching the center point, it has not met the minimally acceptable criteria. If 
the measurement extends beyond the outermost ring, it has exceeded the objective 
criteria. Multiple alternatives can be plotted on the diagram to provide a comparison 
among them in a simple manner. 
Figure 14.2
 provides an example of the radar chart.