Over the past few generations there has been an exponentially increasing investment of human and material resources in scientific inquiry, particularly medical research. Nevertheless, there remains the economists' uncompromising question regarding the actual structure of the relationship between resource investment and product output. In particular, the problem arises of whether, as science progresses, a fixed amount of effort continues to yield uniformly significant results, or whether a process of declining yields is operative in this respect. Even greatly increasing resource investments will fail to generate a corresponding increase in output if the unit cost of production is rising.