A Paradigm for Spreadsheet Engineering Methodologies

Spreadsheet engineering methodologies are diverse and sometimes contradictory. It is difficult for spreadsheet developers to identify a spreadsheet engineering methodology that is appropriate for their class of spreadsheet, with its unique combination of goals, type of problem, and available time and resources. There is a lack of well-organized, proven methodologies with known costs and benefits for well-defined spreadsheet classes. It is difficult to compare and critically evaluate methodologies. We present a paradigm for organizing and interpreting spreadsheet engineering recommendations. It systematically addresses the myriad choices made when developing a spreadsheet, and explicitly considers resource constraints and other development parameters. This paradigm provides a framework for evaluation, comparison, and selection of methodologies, and a list of essential elements for developers or codifiers of new methodologies. This paradigm identifies gaps in our knowledge that merit further research

Spreadsheets Grow Up: Three Spreadsheet Engineering Methodologies for Large Financial Planning Models

Many large financial planning models are written in a spreadsheet programming language (usually Microsoft Excel) and deployed as a spreadsheet application. Three groups, FAST Alliance, Operis Group, and BPM Analytics (under the name “Spreadsheet Standards Review Board”) have independently promulgated standardized processes for efficiently building such models. These spreadsheet engineering methodologies provide detailed guidance on design, construction process, and quality control. We summarize and compare these methodologies. They share many design practices, and standardized, mechanistic procedures to construct spreadsheets. We learned that a written book or standards document is by itself insufficient to understand a methodology. These methodologies represent a professionalization of spreadsheet programming, and can provide a means to debug a spreadsheet that contains errors. We find credible the assertion that these spreadsheet engineering methodologies provide enhanced productivity, accuracy and maintainability for large financial planning models

Research Strategy and Scoping Survey on Spreadsheet Practices

We propose a research strategy for creating and deploying prescriptive recommendations for spreadsheet practice. Empirical data on usage can be used to create a taxonomy of spreadsheet classes. Within each class, existing practices and ideal practices can he combined into proposed best practices for deployment. As a first step we propose a scoping survey to gather non-anecdotal data on spreadsheet usage. The scoping survey will interview people who develop spreadsheets. We will investigate the determinants of spreadsheet importance, identify current industry practices, and document existing standards for creation and use of spreadsheets. The survey will provide insight into user attributes, spreadsheet importance, and current practices. Results will be valuable in themselves, and will guide future empirical research

Intelligent Procedures for Intra-Day Updating of Call Center Agent Schedules

For nearly all call centers, agent schedules are typically created several days or weeks prior to the time that agents report to work. After schedules are created, call center resource managers receive additional information that can affect forecasted workload and resource availability. In particular, there is significant evidence, both among practitioners and in the research literature, suggesting that actual call arrival volumes early in a scheduling period (typically an individual day or week) can provide valuable information about the call arrival pattern later in the same scheduling period. In this paper, we develop a flexible and powerful heuristic framework for managers to make intra-day resource adjustment decisions that take into account updated call forecasts, updated agent requirements, existing agent schedules, agents’ schedule flexibility, and associated incremental labor costs. We demonstrate the value of this methodology in managing the trade-off between labor costs and service levels to best meet variable rates of demand for service, using data from an actual call center

The Lookup Technique to Replace Nested-IF Formulas in Spreadsheet Programming

Spreadsheet programmers often implement contingent logic using a nested-IF formula even though this technique is difficult to test and audit and is believed to be risky. We interpret the programming of contingent logic in spreadsheets in the context of traditional computer programming. We investigate the “lookup technique” as an alternative to nested-IF formulas, describe its benefits for testing and auditing, and define its limitations. The lookup technique employs four distinct principles: 1) make logical tests visible; 2) make outcomes visible; 3) make logical structure visible; and 4) replace a multi-function nested-IF formula with a single-function lookup formula. It can be used only for certain simple contingent logic. We describe how the principles can be applied in more complex situations, and suggest avenues for further research

Fungal growth inside saline-filled implants and the role of injection ports in fungal translocation: In vitro study

WOS: 000224396700022PubMed: 15457030Infection is a serious complication of breast. augmentation and tissue expansion with inflatable devices. Several reports have shown that fungi may be able to survive, colonize, and even cause infection in saline-filled devices. The mechanism of how them, penetrate, spread, and colonize inside the inflatable implants is not exactly understood. The authors assessed both the expander membrane and the port in terms of leakage and penetration of Candida albicans and Aspergillus niger in an in vitro model. Thirty saline-filled expanders connected to the injection port were placed in sterile containers filled with tryptic soy broth culture medium to simulate the clinical situation in phases I and II. Intactand multipunctured ports were used in the first and second phases of the study, respectivelv. Either the container or the implant was inoculated with one of these fungi, and six implants in containers without fungal inoculation served as controls. As a third phase, intraluminal survival of fungi was investigated in saline-filled containers (n = 12) in 21 clays. The silicone membrane, with its intact connecting tube and port, was impermeable to these fungi, whereas both fungi were able to diffuse inside-out or outside-in through the punctured ports. C. albicans did not Survive beyond 18 days in saline, whereas A. niger continued to multiply at day 21. Chemical analyses of the implant fluids revealed that the contents of the culture medium diffused into the implants in phases I and II. The data show that an intact. silicone membrane is impermeable to fungi, and punctured ports allow translocation of fungi into the implants. Fungi can grow and reproduce in a saline-only environment, and their survival periods differ among the species. Furthermore, their Survival maybe enhanced by the influx of substances through the implant shell