The concept of Object Orientation (OO) is very appealing to many in the information systems field. Although it requires a radical shift in the traditional systems development paradigm, many have begun to embrace it. This paper explores the literature on knowledge representation and expertise in the cognitive sciences and in information systems to lend substance to the underlying OO approach. We show that OO closely parallels our current understanding of the concept of expert knowledge representation based on schemata and scripts, and thus is particularly attractive to individuals who are or aspire to be ‘expert’ systems developers. We then examine the IS literature on expertise and reinterpret findings to support our depiction of expertise within IS. The OO approach incorporates many of the characteristics of expert-level knowledge representation, which may explain its appeal to those in the systems development profession. We propose that the OO methodology also contributes to the acquisition of expertise by documenting and sharing the modelling approach of those with considerable IS design expertise.

The use of database systems for managerial decision making often incorporates information-retrieval capabilities with numeric report generation. Of great concern to the user of such a system is the response time associated with issuing a query to the database. This study presents a procedure for estimating response time for one of the most frequently encountered physical storage mechanisms, the indexed file. The model provides a fairly high degree of accuracy, but is simple enough so that the cost of applying the model is not exorbitant. The model incorporates the knowledge that the distribution of access key occurrences is known to follow Zipf's law. It first estimates the access time required to complete the query, which includes the time needed for all input and output transactions, and CPU time used in performing the search. The effects of multiple users on an individual's response time are then assessed using a simple regression estimation technique. The two-step procedure allows for the separation of access time from multiuser influences.

A model of the inverted file of an automated bibliographic system is constructed using the Zipf distribution of word frequency. By ascertaining the parameters of the Zipfian model of the inverted file system, one can estimate the minimum data storage requirements of the database. In addition, given a few additional system parameters, access time for a specified query can be estimated. The estimation procedures are accomplished using logarithmic transformations and multiple regression techniques. This paper introduces the Zipfian models, their regression formulation, and their results and interpretation for application to database evaluation.

A Zipfian model of an automatic bibliographic system is developed using parameters describing the contents of it database and its inverted file. The underlying structure of the Zipf distribution is derived, with particular emphasis on its application to work frequencies, especially with regard to the inverted flies of an automatic bibliographic system. Andrew Booth developed a form of Zipf's law which estimates the number of words of a particular frequency for a given author and text. His formulation has been adopted as the basis of a model of term dispersion in an inverted file system. The model is also distinctive in its consideration of the proliferation of spelling errors in free text, and the inclusion of all searchable elements from the system's inverted file. This model is applied to the National Library of Medicine's MEDLINE. The model carries implications for the determination of database storage requirements, search response time, and search exhaustiveness.

Abstract What does the frequency of occurrence of different words in an article have to do with the number of times an article is cited? Or, for that matter, with the number of publications an author has? All of these—word frequency, citation frequency, and publication frequency‐obey an ubiquitous distribution called Zipf's law. Zipf's law applies as well to such diverse subjects as income distribution, firm size, and biological genera and species. Zipf in 1949 described a hyperbolic rank‐frequency word distribution, which he fitted to a number of texts. He stated that if all unique words in a text are arranged (or ranked) in order of decreasing frequency of occurrence, the product of frequency times rank yields a constant which is approximately equal for all words in a text. The law has been shown to encompass many natural phenomena, and is equivalent to the distributions of Yule, Lotka, Pareto, Bradford, and Price. An ubiquitous empirical regularity suggests some universal principal. This article examines a number of theoretical derivations of the law, in order to show the relationship between the many attempts at ascertaining a theoretical justification for the phenomenon. We then briefly examine some of the ramifications of applying the law to the bibliographic database environment.