ENHANCING DATABASE PERFORMANCE IN A DSS ENVIRONMENT VIA QUERY CACHING

A key element in all decision support systems is availability of sufficiently good and timely data to support the decision making process. Much research was, and is, devoted to data and information quality: attributes, assurance that quality data is used in the decision process, etc. In this paper we concentrate on a particular dimension of data availability and usage -the retrieval of data in a timely and decision enhancing manner. We propose to augment the decision support databases by an adaptive and efficient query cache. The cache contains snapshots of the decision support database, each being the answer to a recently invoked query. A snapshot can be reused by the originating user, or a different user, at a later time --provided the use of cached data leads to savings over the use of a new query, and these savings exceed the cost of using stale date. The proposed scheme is conceptually different from conventional data replication schemes. In data replication schemes the data items to be replicated and the protocols for concurrency control are defined at the system level. In our scheme the cache is populated dynamically and the snapshots it contains are refreshed only if the cost of using stale information is higher than cost of refreshing the snapshots. At the same time, users can still decide to refresh the stored snapshot, based on their own decision environment. Our scheme thus enhances the data retrievalprocess, while supporting a more efficient data retrieval at both the user level and the data warehouse leve

Balancing influence between actors in healthcare decision making

<p>Abstract</p> <p>Background</p> <p>Healthcare costs in most developed countries are not clearly linked to better patient and public health outcomes, but are rather associated with service delivery orientation. In the U.S. this has resulted in large variation in healthcare availability and use, increased cost, reduced employer participation in health insurance programs, and reduced overall population health outcomes. Recent U.S. healthcare reform legislation addresses only some of these issues. Other countries face similar healthcare issues.</p> <p>Discussion</p> <p>A major goal of healthcare is to enhance patient health outcomes. This objective is not realized in many countries because incentives and structures are currently not aligned for maximizing population health. The misalignment occurs because of the competing interests between "actors" in healthcare. In a simplified model these are individuals motivated to enhance their own health; enterprises (including a mix of nonprofit, for profit and government providers, payers, and suppliers, etc.) motivated by profit, political, organizational and other forces; and government which often acts in the conflicting roles of a healthcare payer and provider in addition to its role as the representative and protector of the people. An imbalance exists between the actors, due to the resources and information control of the enterprise and government actors relative to the individual and the public. Failure to use effective preventive interventions is perhaps the best example of the misalignment of incentives. We consider the current Pareto efficient balance between the actors in relation to the Pareto frontier, and show that a significant change in the healthcare market requires major changes in the utilities of the enterprise and government actors.</p> <p>Summary</p> <p>A variety of actions are necessary for maximizing population health within the constraints of available resources and the current balance between the actors. These actions include improved transparency of all aspects of medical decision making, greater involvement of patients in shared medical decision making, greater oversight of guideline development and coverage decisions, limitations on direct to consumer advertising, and the need for an enhanced role of the government as the public advocate.</p

USE OF STALE ANSWERS IN DATABASE APPLICATIONS

In a typical database application, it is commonly assumed that user information requirements can only be satisfied by the most current data. The desirable attributes of infolmation often include being up-to-date, timeliness, and accuracy, with the implicit assumption that without these attributes a response to a query has little or no value. This assumption is challenged in this work. We consider the tradeoff between the cost of incomplete information, due to the use of stale data, and the incremental cost of providing a current answer. We propose that the database system be extended to include a data cache, in which copies of frequently needed data will be kept. Objects in the cache are not updated as the database changes, but rather are refreshed whenever the cost of using stale data exceeds some prespecified level. We also discuss alternative refresh policies and cache search schemes

Optimization of the Arbitrage Process in Advance Refunding of Municipal Bonds

States, municipalities, and other regional or local public bodies have the authority to issue debt securities, the interest on which is tax exempt under federal regulations. As a consequence, the interest which these entities must pay on their bonds is usually below the rate on U.S. government securities of identical maturity. Arbitrage bonds--issued by a municipality to take advantage of this differential--are not generally permitted, with the exception of Advance Refunding. Advance Refunding is the process by which the proceeds of a municipal bond issue are invested in Treasury securities and these securities placed in a trust fund to pay when due the principal and interest on debt previously outstanding. To limit the arbitrage profit to the municipality engaging in Advance Refunding, the U.S. government has strictly limited the amount of the new issue which may be invested at a yield rate greater than the rate obtained on the new municipal debt. This article, after discussing the appropriate government regulations, provides a simple example of Advance Refunding and a theoretical analysis of a simple refunding scheme. It then describes a two stage optimization procedure which will maximize the savings to the municipality which chooses to Advance Refund its debt. Results of this new procedure, which first minimizes the amount of Treasury securities and then provides an optimal maturity schedule for the new debt, are compared with actual refundings using other programs.