Pay includes benefits such as vacation and sick days. It illegal for employers with 15 or more employees to discriminate with regard to wages on the basis of race, religion, national origin, disability and age. Skill is measured by factors such as the experience, ability, education and training required to perform the job. The key issue is what skills the job requires, not what skills the individual employees may have. A waitress with a master's degree is not entitled to more pay than a waitress without a master's degree.
Effort refers to the amount of physical or mental exertion needed to perform the job.
For example, the job of the person at the end of an assembly line who must lift the assembled product and place it on a board requires more effort than the other assembly line jobs. If the extra effort of lifting the assembled product off the line is substantial and is a regular part of the job, increased pay for that position is justified. Responsibility is the degree of accountability required in performing the job. For example, a salesperson who is delegated the duty of determining whether to accept customers' personal checks has more responsibility than other salespeople. On the other hand, a minor difference in responsibility, such as assignment of the task of locking up at the end of the day, would not justify a pay differential.