In effectively managed companies, the answer to the question of whether employees should be perceived as cost or as investment, is obvious. Investment should be made in human resources as this allows for reducing the cost of company's activities, increasing its effectiveness, efficiency, etc. A similar question can be put for machine operation, but here the answer is not so straightforward. The conflict between production managers and machine maintenance managers still exists; it is usually settled with the production side winning. This paper is an attempt to assess the effectiveness of machine operation and the effectiveness of the whole company based on an analysis of so called OEE (Overall Equipment Effectiveness) index, calculated from a timekeeping study of a big food producing company.