Heteroskedasticity-Consistent Estimation of the Variance-Covariance Matrix for the Almost Ideal Demand System

In this note I demonstrate the previously overlooked fact that if the AIDS aggregate demand model is constructed as the aggregation of individual consumer demands, then the error structure for any individual equation is necessarily heteroskedastic unless the distribution of income is constant across aggregates. Maximum likelihood estimation which ignores this heteroskedasticity yields inconsistent estimates of the variance-covariance matrix and renders likelihood ratio tests of the restrictions of consumer demand theory inappropriate. A heteroskedasticity-consistent estimator of the variance-covariance matrix is proposed by adopting the technique of White (1980) to the case at hand.

Productivity Growth in the Automobile Industry, 1970-1980: A Comparisonof Canada, Japan and the United States

In this paper we calculate and analyze the automobile industries cost and productivity experience during the 1970 's in Canada, the U.S.and Japan. Utilizing an econometric cost function methodology, we are able to isolate the major source of short-run disequilibrium in this industry-variations' in capacity utilization-and analyze its effects on cost and total factor productivity (TFP) gross. This is achieved through a novel application of the Viner-Wng envelope theorem, which allows us to track short-run behavior utilizing what is essentially a long-run cost function.To striking empirical results energe. First, TFP grew much faster in the Japanese automobile industry (4.3% annum) than in the Canadian (1.4%) and U. S.(1.6%) industries. Second, the importance in analyzing variations in capacity utilization is confinned by the fact that failure to correct for this source of productivity change would have led to a 31% under estimate of long-run TFP growth in Canada arid a 37% underestimate for the United States.

The Extent and Sources of Cost and Efficiency Differences Between U.S. and Japanese Automobile Producers

In this paper we present for the first time estimates of cost and efficiency differences between U.S. and Japanese producers based on an econometric cost function methodology rather than the accounting frameworks previously used. We demonstrate that the cost difference estimates for 1979 which were influential in the debate that resulted in the Voluntary Restraints Agreements of 1981-85 were substantial over estimates of the Japanese advantage. While our estimate of the Japanese cost advantage for 1980 is similar to previous estimates, we attribute most of this advantage to short-run phenomena -underutilization of U.S. production capacity and an undervalued yen. In a previous paper we have shown that the Japanese TFP growth rate was much faster than the U.S. rate during the 1970's. However we estimate the long-run underlying Japanese efficiency advantage as of 1980 to have been only 1-2%, much less than previously estimated. This results from the fact that Japan began the 1970's with a long-run efficiency disadvantage of over 20%, and the decade of the 1970's represented a catch-up period for Japanese producers.

Productivity measurement using capital asset valuation to adjust for variations in utilization

Also released as Working Paper No. 8125, Institute for Policy Analysis, University of Toronto. *An earlier version was presented at the econometric Society Summer Meetings, San Diego, California, June 24-27, 1981.Although a great deal of empirical research on productivity measurement has taken place in the last decade, one issue remaining particularly controversial and decisive is the manner by which one adjusts the productivity residual for variations in capital and capacity utilization. In this paper we use the Marshallian framework of a short run production or cost function with certain inputs quasi-fixed to provide a theoretical basis for accounting for variations in utilization. The theoretical model implies that the value of services from stocks of quasi-fixed inputs should be altered rather than their quantity. This represents a departure from previous procedures that have adjusted the quantity of capital services for variations in utilization. In the empirical illustration, we employ Tobin's q to measure the shadow value of capital, and find that for the U.S. manufacturing sector, we can attribute 25% of the traditionally measured decline in productivity growth during 1973-77 to a decline in capacity utilization.Research supported by the Department of Energy, under Contract EX-76-A-Ol-2295, Task Order 67

Economic Capacity Utilization and Productivity Measurement for Multi-product firms with multiple quasi-fixed inputs

In this paper we develop measures of economic capacity output and economic capacity utilization for firms producing multiple outputs and having one or .ore quasi-fixed inputs. Although we produce an impossibility theorem showing that based only on the assumption of cost minimization, the concept of capacity output is undefined whenever the number of outputs I exceeds the number of fixed inputs M, we are able to provide alternative constructive procedures for defining capacity output whenever I [is less than] M. We also propose a number of additional primal and dual measures of utilization of the variable and fixed inputs, including a multi-fixed input analog to Tobin's q. We relate these alternative utilization measures to one another, and show that unambiguous inequality relationships among them (relative to unity) can typically be specified a priori only under rather restrictive assumptions. We show that unless restrictive assumptions are made. the multi-fixed input analogs to Tobin's q have little informational content regarding incentives for net investment of any specific fixed input. Finally, we demonstrate the usefulness of the alternative utilization measures by showing how they can be incorporated to adjust traditional measures of multi factor productivity growth for variations in short-run utilization.

Productivity Growth in Canadian Telecommunications.

Canadian telecommunications firms do not price proportionately to marginal cost. The prices of toll services tend to be above marginal costs, whereas the prices of basic local services are typically set below marginal costs by regulators. In such circumstances, estimates of TFP growth using the conventional Tornqvist (Divisia) formula which weights outputs by revenue shares in determining the rate of growth of aggregate output is theoretically incorrect and needs to be replaced by a formula which uses cost elasticity weights. Empirically, the conventional Tornqvist index yields a very distorted picture of efficiency gains in the two largest Canadian telephone companies during the 1980s. For Bell Canada, I calculate the upward bias to be approximately 75 percent over the period 1980-89 and 80 percent over the period 1985-89. For B.C. Tel a similar calculation yields an upward bias of 37 percent over the period 1980-89 and 48 percent over the period 1985-89.