Every year, managers dutifully haul their employees in for the dreaded performance assessment. These invariably prove to be torture sessions for employees, who are forced to sit there while a manager recounts a year's worth of missteps or gropes for ways to point out their faults without causing offense. Managers, too, resent being asked to summarize something as complex as performance by checking off boxes, an exercise that's followed by the occasionally combative process of justifying their marks. Almost always, both parties walk away from the session unenlightened and dissatisfied.

Yet for those who can stomach it, there's a lot to be learned and accomplished through these evaluations—whether the subject is a job candidate or a staff member. Handled properly, the assessment can be an invaluable method of evaluating the worker's potential to be useful to the company, and then, of assuring that the person is allowed to fulfill his or her potential. Problem is, most people don't do a very good job of it—largely because they've neglected the groundwork. Here are some ways to start assessing for success:

1. Train the assessors. Not everyone is skilled at assessment. There's an art to putting aside personal opinions and looking at things from the organization's perspective. You have to know both what to look for and what questions to ask. You also must know how to consider both qualitative and quantitative evidence. Assess the assessors and provide training, where necessary.

2. Assess the tools you're using. The list of available assessment tools grows longer by the day. At the click of a mouse, you can find software applications that identify strengths and weaknesses, distinguish personality types, isolate unique talents, detect someone's level of integrity and probe for key behavioral traits. There are examinations that measure clerical skills, light industrial skills, mechanical abilities and, of course, computer skills. But don't put too much faith in these tools. Recently, the vice president of a small distribution center relayed an experience he had with a new employee: "The best interview I ever had," he said of her pre-employment evaluation." But within a week after she began work, we found out she was a lunatic, screaming through the halls and showing other signs of erratic behavior." Even her eventual dismissal didn't make the problem go away. Although the company kept prevailing at her unemployment hearings, the former employee kept appealing. It was a nightmare.

3. Assess the organization's focus. Too many managers embark on the hiring process armed only with a vague and outdated job description. Take a hard look at that description and list of requirements. Rewrite it to express the goals and objectives clearly, if necessary. Then re-evaluate it on a regular basis. Like any good virus, the business world is constantly adapting and changing to ensure its survival. Whether you're recommending that you stay the course or veer off in a new direction, you should be confident you can defend your position to yourself and to your department, division and company.

4. Assess the organization's resources. Though there's some truth to the proverb, " It is a poor workman who blames his tools," it's also true that equipment or resource problems can bring operations to a halt. A computer system that is regularly down not only hinders performance but also causes frustration.

5. Assess your priorities. It's no wonder staff members get so confused: They get one message about the company's priorities through its advertising, marketing and customer service materials. Then, they come to work and are told to act upon departmental priorities. Make sure everyone is working toward the same goal.