amount of time to change a bandage or college professors the same amount of time to mark an essay today as it did in 1966, as those types of activities rely on the movements of the human body, which cannot yet be engineered to perform more quickly, accurately, or efficiently in the same way that a machine, such as a computer, have. In contrast, goods-producing industries, such as the car manufacturing sector and other activities that involve routine tasks, workers are continually becoming more productive by technological innovations to their tools and equipment. The reported productivity gains of the service industry in the late 1990s are largely attributable to total factor productivity. Providers decreased the cost of ancillary labor through outsourcing or technology. Examples include offshoring data entry and bookkeeping for health care providers and replacing manually-marked essays in educational assessment with multiple choice tests that can be automatically marked. Technical description In the 1967 paper Macroeconomics of Unbalanced Growth: The Anatomy of Urban Crisis, Baumol introduced a simple two-sector model to demonstrate the cost disease. To do so, he imagined an economy consisting of only two sectors: sector one, which has constant productivity (that is, the number of goods workers can produce per man hour does not change as time goes on), and sector two, which sees productivity grow at a constant compounded rate (that is, the number of goods workers can produce per man hour grows at a rate , where is time). To simplify, he assumed that the quantity of goods produced by these two sectors (the "output" of each of the two sectors) is directly proportional to the quantity of labor employed (that is, doubling the number of workers doubles the output, tripling the number of workers triples the output, and so on) and that output depends only upon labor productivity and the quantity of labor. Since there is no increase in labor productivity in sector one, the output of sector one at time (denoted ) is: where is the quantity of labor employed in sector one and is a constant that can be thought of as the amount of output each worker can produce at time . This equation simply says that the amount of output sector one produces equals the number of workers in sector one multiplied by the number of goods each worker can produce. Since productivity does not increase, the number of