Driving your employees' creativity while keeping them productive is an ongoing battle.

Robert Epstein, senior research psychologist at the American Institute for Behavioral Research and Technology, offers a solution to the often-vexing problem. He writes in Harvard Business Review about how you can train your employees to be more creative by teaching core creative competencies.

Epstein says that after he trained employees of a small California city, managers reported that they were receiving 55 percent more new ideas. City officials attributed $600,000 in new revenue and $3.5 million in savings to the training.

So what makes this kind of training so effective?  From his studies of more than 1,300 managers in 19 countries, Epstein came up with eight core creative competencies you can use with your staff. See below and start training your employees to tap their best ideas.

1. Institute ongoing education and development

You should be constantly training employees in skills that are outside of their expertise and job title. You want versatile professionals who are not confined to a box. Help them expand their knowledge and skill set by offering weekly training sessions on various topics.

2. Record all ideas

You and your employees should keep a daily record of unedited, off-the-cuff ideas. Keep a document open and add to it every day. Do not censor any ideas, within reason. Then each month dig through and see if you can make something out of them.

3. Manage your surroundings

This may sound trivial, but you should surround yourself and your employees with "diverse and novel physical and social stimuli," Epstein says. The right environment will drive creativity.

4. Seek out challenges

Epstein says you need to give your employees "difficult problems to solve and ambitious goals to reach," but you also have to help them manage the stress. Deliberately seek hard projects and "manage failure constructively." Do not yell at your employees for trying and failing. You should help them find the lesson and thank them for trying something new. Eventually, this approach will create a fertile, creative environment where employees are trying new things and creating new business.