Abstract: A method of carrying out activity based costing in a professional practice, such as a healthcare practice or hospital is provided. The costs of activities involving an operator are calculated based on the time the operators should be expected to spend on a task, and the cost overhead, particularly the payment, of the operator. This is achieved using a Pre-Determined Motion Time System such as the MOST® system. This allows the inherent profitability of a business operation to be established independent of the current employees, so that the profitability of the business processes themselves can be ascertained.