In this paper, we examine the sources of the productivity growth in the U.S. computer industry from 1978 to 1999. We estimate a joint production model of output quantity and quality that distinguishes two types of technological changes: process and product innovations. Based on the estimation results, we decompose total factor productivity (TFP) growth rate into the contributions of process and product innovations and scale economies. We find that product innovation associated with better quality accounts for about 30% of the TFP growth in the computer industry. Furthermore, the TFP acceleration in the computer industry in the late 1990s is mainly derived from a rapid increase in product innovation.

This paper examines the sources of productivity growth for the, U.S. telecommunications industry from 1935 to 1987. These years encompass both the pre-and post-AT&T divestiture periods. We formulate a structural model that accounts for both changes in the cost and the demand side of the industry. We measure the contributions of aggregate demand, information intensity of the economy, price-cost margins, relative factor prices, direct and indirect effects of technological progress, and R&D investment on total-factor productivity (TFP) growth rate. We show that TFP growth rate as conventionally measured is a seriously biased measure of rate of technical change in this industry.