This debate has increased in intensity over the years as some planners have sought to objectify asset allocation to the point where conceptual thinking and judgment are de-emphasized.

The latest manifestation of this movement is the myriad variations of software sold to do the job that financial advisers have been doing for decades with pencils and calculators. Now, some planners and financial services firms are using software programs called "optimizers" to configure clients' allocations.

Though there's nothing wrong with using software to take the numerical drudgery out of the task, these optimizers pose a problem: They lend an air of scientific certainty to a task that necessarily involves the subjective. If asset allocation were indeed a pure science, then most or all optimizers would render the same configuration when fed data about the same investor. But they don't. Optimizer results tend to vary widely, and the slightest change in input data can yield greatly disproportionate results.

Regardless of whether you use a financial planner's experience or a newfangled optimizer to develop your asset-allocation plan, the process will involve judgments. With the optimizer, the judgments have been incorporated into the programs -- often without the inflexibility to deal with the many shades of difference between one investor's situation and another's.

And just as the style of financial management will vary from one advisor to the next, so too will the styles of the professionals who develop optimizers. If anything, optimizers are a standardized solution to a problem that is anything but standard. The matrix of possible asset allocations is virtually infinite, but there are only so many optimizers on the market, and each has only so many variables to choose from.

Instead of using pseudo-science, look for experience and training in your adviser. If you're thinking of developing your asset allocation without professional assistance, be prepared to do a lot of reading -- even if you're a highly knowledgeable amateur investor. And be prepared to make some costly mistakes -- literally.

Next: Take the test