total factor productivity (TFP)的公式是什么？

问题如下：

N'Diarra, who has studied the Cobb–Douglas production function, believes that Sagara's primary goal should be to raise the growth rate of per capita GDP. Her two recommendations, therefore, are to

1. increase capital, and

2. invest in technology to raise total factor productivity (TFP).

N'Diarra adds this conclusion:

"Because the Cobb–Douglas function exhibits constant returns to scale, as we approach the steady state rate of growth, we should place greater emphasis on continuing to grow TFP in order to avoid diminishing marginal returns on capital."

In reference to the Cobb–Douglas function, N'Diarra's conclusion is best described as:

选项：

A.incorrect because increased TFP is not subject to the law of diminishing returns. B.incorrect because the Cobb–Douglas function does not exhibit constant returns to scale. C.correct.

解释：

The stated conclusion is accurate in its entirety. The Cobb–Douglas function exhibits constant returns to scale, which means that if all inputs are increased at the same percentage, then output rises at that percentage. Diminishing marginal productivity exists with respect to each individual input (if the other input is held constant). Continued growth in per capita output is possible even in the steady state as long as there is ongoing technological progress (increases in TFP).