Monitoring the mean and the variance of a stationary process

We deal with the problem of how deviations in the mean or the variance of a time series can be detected. Several simultaneous control charts are introduced which are based on EWMA (exponentially weighted moving average) statistics for the mean and the empirical variance. The combined X − S² EWMA chart is extended to time series. Further simultaneous charts are considered. The comparision of these schemes shows that the residual attempt must be favored if a variance change is present.     

Economic progress and skill obsolescence with network effects

Summary. We construct an OLG model with network effects to examine skill obsolescence when individuals can choose technological vintages. In the absence of transfer payments, some regions of the parameter space have unique stationary equilibria, others have unique cyclical equilibria, and others have multiple stationary equilibria. All equilibria are Pareto efficient. However, rat race equilibria can exist in which all agents currently alive prefer a slower rate of progress than occurs in equilibrium. When contemporaneous transfers are allowed, equilibria are unique everywhere, but a cycle still exists, and a rat race can still arise in equilibrium. Allowing intertemporal transfers (debt) ensures that all equilibria are stationary. In the relevant parameter range, the introduction of debt can eliminate cycles and increase the long-run growth rate. No rat race equilibria exist when debt is allowed.Received: 3 January 2002, Revised: 3 June 2004, JEL Classification Numbers: 041, J24, O33. Correspondence to: Ian P. KingEarly versions of this paper were presented at the West Coast Macro Workshop, the Mid-West Macro Meetings, the Canadian Macroeconomics Study Group Meetings, and the Society for Economic Dynamics Meetings. We would like to thank V. V. Chari, Merwan Engineer, Don Ferguson, John Hillas, John Knowles, Dan Peled, Dan Usher, Linda Welling and Julian Wright for helpful comments. We are especially grateful to an anonymous referee for some very useful and substantive comments.     

Assessing the impact of patent infringement on new product sales

In order to assess the impact of patent infringement on the growth of a new product, a model is developed through the intervention model development processes of Box-Jenkins and Box-Tiao. Physical interpretations of model parameters and determination of associated damages suggest that the model can provide a sound basis for analyzing patent infringement disputes.     

Regulatory Uncertainty and Share Price Volatility: the English and Welsh Water Industry’s Periodic Price Review

This paper models the London stock markets response to the 1994 Periodic Review of prices in the English and Welsh water industry using both GARCH and stochastic volatility models. The results indicate that a significant reduction in the volatility of share prices for eight of the ten water and sewerage companies followed the announcement of revised industry price-caps. Investor expectations adjusted rapidly, reflecting confidence in the credibility and political sustainability of the settlement.     

The relationship between performance appraisal criterion specificity and statistical evidence of discrimination

Plaintiffs' expert witnesses in EEO cases involving performance appraisals often claim that adverse impact is a result of the type of rating format used. Their theory is that more specific rating criteria will lead to lessened adverse impact. We tested that theory by comparing data from a simple category‐based rating system against data from a standards‐based Work Planning and Review appraisal system with over 248,000 performance appraisals of state employees. Using logistic regression and statistical definitions of prima facie discrimination, we found no support for the hypothesis that adverse impact is materially affected by criterion specificity. © 2003 Wiley Periodicals, Inc.     

The effect of rule 12b-1 on bond fund expense ratios

This paper presents empirical evidence that bond mutual funds which have adopted the use of 12b-1 fees have not achieved the goal of lowering expense ratios. Using a model specific to bond funds, as opposed to generic models used in previous studies on equity funds, the analysis confirms that the 12b-1 fee is an additional cost borne by shareholders of the fund without any additional benefit. However, this cost as a percent of the net asset value of the fund has decreased from 1991 through 1994. This reduction coincides with the submission of a proposed rule change by the National Association of Security Dealers concerning maximum sales charges imposed by mutual funds on December 28, 1990 and the implementation of limits on 12b-1 fees which became effective in July of 1993.     

Macroeconomic forecasting using structural factor analysis

The use of a small number of underlying factors to summarize the information from a much larger set of information variables is one of the new frontiers in forecasting. In prior work, the estimated factors have not usually had a structural interpretation and the factors have not been chosen on a theoretical basis. In this paper we propose several variants of a general structural factor forecasting model, and use these to forecast certain key macroeconomic variables. We make the choice of factors more structurally meaningful by estimating factors from subsets of information variables, where these variables can be assigned to subsets on the basis of economic theory. We compare the forecasting performance of the structural factor forecasting model with that of a univariate AR model, a standard VAR model, and some non-structural factor forecasting models. The results suggest that our structural factor forecasting model performs significantly better in forecasting real activity variables, especially at short horizons.     

Restructuring materiel management functions: a method for prioritizing changes and reducing costs

The success of any manager depends highly on the ability to seize on opportunities that will achieve the organization's goals. Hospitals are currently searching for ways to reduce costs while maintaining or enhancing the quality of services. Quality services are increasingly being defined as those that are most responsive to customer needs. It is important, as hospital management restructures materiel systems or methods of operation for reduced costs, to focus on the user departments as the customers. The consolidation of materiel management activity should not be seen as a loss of control at the user department level. Instead it can be seen as a new way of providing service with higher quality. User departments should see concrete benefits on a weekly basis, including reduced time spent on materiel management functions; increased planning of purchasing, inventory, and distribution functions; and assistance in meeting restricted supply budgets.     

"No fear" fund raising

Successfully asking for a major gift requires practice. We only raise major gifts by asking and that requires us to get out there in front of major gift prospects. We must discipline ourselves to do just that. Being a successful major gift fund raiser requires continual practice.