The effects of Six Sigma on corporate performance: An empirical investigation

The purpose of this study is to investigate the impact of adopting Six Sigma on corporate performance. Although there is a fairly large and growing body of anecdotal evidence associated with the benefits of implementing Six Sigma, there is very little systematic and rigorous research investigating these benefits. This research extends previous research in several important ways including utilizing a sample of 84 Six Sigma firms that represent a wide variety of industries and firm characteristics, utilizing rigorously constructed control groups to ensure the validity of our comparisons and conclusions, and investigating the impact of adopting Six Sigma on corporate performance over a ten year period. To carry out this investigation, the event study methodology is employed. The ten year period consists of three years prior to Six Sigma implementation, the event year corresponding to the year Six Sigma is adopted, and six years post Six Sigma implementation. To assess the impact of adopting Six Sigma on corporate performance we utilize commonly used measures including Operating Income/Total Assets (OI/A), Operating Income/Sales (OI/S), Operating Income/Number of Employees (OI/E), Sales/Assets (S/A), and Sales/Number of Employees (S/E). The sample Six Sigma firms are compared to different benchmarks including the overall industry performance and to the performance of carefully selected portfolios of control firms. The results of the study indicate that adopting Six Sigma positively impacts organizational performance primarily through the efficiency with which employees are deployed. More specifically, enhanced employee productivity results were observed in both static analyses that assessed the performance of the sample Six Sigma firms relative to their control groups at discrete points in time and dynamic analyses of the Six Sigma firms’ rate of improvement relative to the rate of improvement of their control groups. Benefits in terms of improved asset efficiency were not observed. Finally, there was no evidence that Six Sigma negatively impacts corporate performance.     

SCALE ECONOMIES IN MULTIPRODUCT FIRMS

As normally employed, multioutput cost functions impose a bias against a finding of economies of scale, because a firm's optimal expansion path generally does not entail constant proportions over the various outputs. This bias can be overcome using a cost function defined in terms of a scalar aggregate output. An empirical example using New York commercial banks bears out the argument. As a sidelight, it is also argued that the traditional concept of scale economies is appropriate for policy purposes even when it conflicts with the more recently developed condition of natural monopoly (subadditivity of the cost function).     

Equity duration and convexity when firms can fail or stagnate

Previous analysis of equity duration and convexity has either ignored the risk that firms can fail or stop growing, or else has incorporated the risk of failure in an ad hoc way. This paper derives equity duration and convexity rigorously corrected for the risk of failure or stagnation. We show that the correction is large enough to be important in standard applications. Further, equity duration is unaffected by any liquidation payout at the time of failure.