Salaries Need To Be Fair, Which Does Not Always Mean Equal

• First, employees are very impacted by differences of salary within their peer groups.
• Second, this effect does not happen when employees learn that their managers and boss earn even significantly more money than they do.

The key is to think in term of fairness (same salary for the same responsibility, and never forgetting that employees care mostly about their standing in a specific reference group — their peers), which does not hinder you from using money as an incentive to get a promotion.