Orthogonal Array is a Testing Design Technique where u can 
give 90% Test Coverage.Here Functionalities are seperated 
into "Factors" and "Levels" and out put will be in the form 
of "Experiments".Its a misunderstandindg that the no of 
Test cases will be reduced always in Orthogonal Array.It's 
not the way always.It gives the effective Experiments/T.C 
to be executed ,some times it may list more no of T.C than 
u identified manually.
Objective:
Reduce COST,REWORK,TIME
Increase Productivity
MAX Test Coverage