A non-homogeneous hidden Markov model for precipitation occurrence

A non-homogeneous hidden Markov model is proposed for relating precipitation occurrences at multiple rain-gauge stations to broad scale atmospheric circulation patterns (the so-called 'downscaling problem'). We model a 15-year sequence of winter data from 30 rain stations in south-western Australia. The first 10 years of data are used for model development and the remaining 5 years are used for model evaluation. The fitted model accurately reproduces the observed rainfall statistics in the reserved data despite a shift in atmospheric circulation (and, consequently, rainfall) between the two periods. The fitted model also provides some useful insights into the processes driving rainfall in this region.     

Comment

A vector autoregression is a reduced-form representation and therefore would be expected to change when any structural equation in the system changes, regardless of whether economic decisions are forward-looking. Even so, a dynamic simulation of a model with unit roots will exhibit large cumulative errors, making it difficult to detect whether a structural change has indeed occurred.     

A simulation system for corporate planning

This paper describes the structure and use of a general purpose simulation package developed for the interactive construction of dynamic computer-based simulation models. The package consists of a system of computer programs written in the BASIC language for a Digital PDP 11/70 time-sharing computer.The framework upon which the package is based is essentially an amalgamation of the System Dynamics and Input-Output approaches to the modelling of complex organizations. Networks of levels and flows provide the basis for dynamic, modular representation, while matrix algebra features provide the basis for aggregational flexibility and the analysis of multi- product multi-process industrial systems.The package is designed to provide planning managers with the ability to construct flexible models, localized or ‘corporate’, financial or non-financial, without the need for any programming in the conventional sense. A flow diagram of the system to be modelled guides the model builder in responding to computer terminal prompts which determine the model structure as a set of programmed relationships. This in turn gives rise to a further series of prompts at the terminal for the entry of all data pertinent to the model. Model editing and computation then proceeds, with user interaction, if desired, for amendments, monitoring of computations, and report generation.Two specific applications of the package are discussed in the latter part of the paper, and sample output from runs of both of the resultant models is provided.     

A Note on Consistency in Utility Assessment*

A methodology for determining a von Neumann-Morgenstern utility function is outlined based on the axioms crucial to such a function. Reconciliation of inconsistent judgments is facilitated using the theory of reciprocal matrices. Numerical measures of the collective divergence of a set of judgments from perfect consistency or coherency are provided.     

Applications and Implementation DECISION SUPPORT SYSTEMS: AN EMPIRICAL ASSESSMENT FOR DECISION MAKING

A laboratory experiment examined the effects of applying decision support system (DSS) technology to decision making in ill-structured problem environments under varying information conditions. Marketing executives participated in the experiment which investigated the effects of DSS availability, DSS training, and data availability on dependent variables that included: (1) the number of alternatives considered by a subject during decision making, (2) the period of time spent by a subject to complete the decision-making process, (3) the subject's perceived confidence in the decisions he or she had made, (4) the amount of data considered by a subject's during decision making, (5) the individual subject's decision processing, and (6) the subject's performance overall. Our results indicate that all three factors significantly affect the number of alternatives considered by subjects during the decision-making process. We therefore suggest that DSS training be coordinated with decision training in order to realize the potential of DSSs as described in the DSS literature.     

A Note on Interpersonal and Communication Skills for IS Professionals: Evidence of Positive Influence

A recent article by Byrd and Turner (2001) reported that interpersonal skills on the part of information systems personnel had a negative influence on the success of systems as measured by competitive advantage. Several reasons were forwarded to account for this unexpected result, including lack of richness in the measure of these skills, the use of strategic success measures, the true complexity of interpersonal relations within an organization, and the sample of CIOs who may have a bias in favor of technical skills. We address these concerns by incorporating a set of communication skills into the interpersonal skills set, sampling users for a different set of stakeholders, and employing a more complex model based on theories of expectation. The results indicate that the impacts of interpersonal skills on system success is not a simple function of the perceived level of the IS staff's skill proficiency but is also determined by the understood expectations of skill requirements.