Joint outputs and real wage rates

The magnification effect in standard international trade theory asserts that if the relative price of the labor-intensive commodity increases, the real wage will also increase, as will the wage/rental ratio. This result depends upon the assumption that both activities are nonjoint—each combining labor and capital to produce a single output, so that if activities are joint instead, the results are in jeopardy. It is shown that if the difference between the share of commodity one produced in the first activity and in the second activity exceeds the difference between the labor distributive shares in the first activity and the second, an increase in commodity 1's relative price raises the wage/rental ratio. The real wage unambiguously rises in this case if and only if the ratio of the commodity output shares in the two activities exceeds the ratio of labor shares.