The issue is to divide a complex design problem, such as a car or airplane, into manageable subproblems. Subdividing a large problem usually creates the need for a lot of communication between separate designers assigned to each subproblem and often results in search, iteration, backtracking and wasted time. Since real designs are usually too complex for one person to solve alone, this problem occurs all the time. The issues are to identify good subproblems into which to split a big problem, and then to determine a sequence in which the subproblems should be solved or the order in which values for the individual design variables should be determined. This is both an engineering and a management science problem.
Several techniques appear promising.
One involves interviewing designers to find out what information they need before they can start their subproblem and what information they can provide when they are done. Since this is almost never possible, a lot of imperfect options must be discovered and studied. Designers in such a study often discover that they have been talking to the wrong people or giving out information that is too late or never used. Re-ordering the subproblems results in more efficient parameter passing, the need for fewer parameters to be passed, or passing of less sensitive parameters so that the solution converges faster. This method would work if the subproblem solutions were close to the total solution.