Tia and Eric went to trade school at the same time. Each graduated with an associate's degree. They have received similar performance evaluations. Eric's employer is not a good business manager, and the sales manager lost a major deal. Because of the decrease in profits, the employees did not receive raises last year. Tia's employer is a savvy business manager and the sales manager is experienced and works hard. If Tia has higher earnings than Eric, the difference is most likely a function of