A software technology evaluation program

A set of quantitative approaches is presented for evaluating software development methods and tools. The basic idea is to generate a set of goals which are refined into quantifiable questions which specify metrics to be collected on the software development and maintenance process and product. These metrics can be used to characterize, evaluate, predict, and motivate. They can be used in an active as well as passive way by learning form analyzing the data and improving the methods and tools based upon what is learned from that analysis. Several examples were given representing each of the different approaches to evaluation. The cost of the approaches varied inversely with the level of confidence in the interpretation of the results

A practical experience with independent verification and validation

One approach to reducing software cost and increasing reliability is the use of an independent verification and validation (IV & V) methodology. The Software Engineering Laboratory (SEL) applied the IV & V methodology to two medium-size flight dynamics software development projects. Then, to measure the effectiveness of the IV & V approach, the SEL compared these two projects with two similar past projects, using measures like productivity, reliability, and maintain ablilty. Results indicated that the use of the IV & V methodology did not help the overall process nor improve the product in these cases

An empirical study of software design practices

Software engineers have developed a large body of software design theory and folklore, much of which was never validated. The results of an empirical study of software design practices in one specific environment are presented. The practices examined affect module size, module strength, data coupling, descendant span, unreferenced variables, and software reuse. Measures characteristic of these practices were extracted from 887 FORTRAN modules developed for five flight dynamics software projects monitored by the Software Engineering Laboratory (SEL). The relationship of these measures to cost and fault rate was analyzed using a contingency table procedure. The results show that some recommended design practices, despite their intuitive appeal, are ineffective in this environment, whereas others are very effective

Structures and materials technology for hypersonic aerospacecraft

Major considerations in structural design of a transatmospheric aerospacecraft are discussed. The general direction of progress in structures and materials technology is indicated, and technical areas in structures and materials where further research and development is necessary are indicated. Various structural concepts under study and materials which appear to be most applicable are discussed. Structural design criteria are discussed with particular attention to the factor-of-safety approach and the probabilistic approach. Structural certification requirements for the aerospacecraft are discussed. The kinds of analyses and tests which would be required to certify the structural integrity, safety, and durability of the aerospacecraft are discussed, and the type of test facility needed to perform structural certification tests is identified

An approach for assessing software prototypes

A procedure for evaluating a software prototype is presented. The need to assess the prototype itself arises from the use of prototyping to demonstrate the feasibility of a design or development stategy. The assessment procedure can also be of use in deciding whether to evolve a prototype into a complete system. The procedure consists of identifying evaluations criteria, defining alterative design approaches, and ranking the alternatives according to the criteria

Studies and experiments in the Software Engineering Lab (SEL)

The Software Engineering Laboratory (SEL) is an organization created nearly 10 years ago for the purpose of identifying, measuring and applying quality software engineering techniques in a production environment. The members of the SEL include NASA/Goddard Space Flight Center (GSFC, the sponsor and organizer), University of Maryland, and Computer Sciences Corporation. Since its inception the SEL has conducted numerous experiments, and has evaluated a wide range of software technologies. This paper describes several of the more recent experiments as well as some of the general conclusions to which the SEL has arrived

Designing with Ada for satellite simulation: A case study

A FORTRAN oriented and an Ada oriented design for the same system are compared to learn whether an essentially different design was produced using Ada. The designs were produced by an experiment that involves the parallel development of software for a spacecraft dynamics simulator. Design differences are identified in the use of abstractions, system structure, and simulator operations. Although the designs were vastly different, this result may be influenced by some special characteristics discussed

Criteria for software modularization

A central issue in programming practice involves determining the appropriate size and information content of a software module. This study attempted to determine the effectiveness of two widely used criteria for software modularization, strength and size, in reducing fault rate and development cost. Data from 453 FORTRAN modules developed by professional programmers were analyzed. The results indicated that module strength is a good criterion with respect to fault rate, whereas arbitrary module size limitations inhibit programmer productivity. This analysis is a first step toward defining empirically based standards for software modularization

Designing with Ada for satellite simulation: A case study

A FORTRAN-operated and an Ada-oriented design for the same system are compared to learn whether an essentially different design was produced using Ada. The designs were produced by an experiment that involves the parallel development of software for a spacecraft dynamics simulator. Design differences are identified in the use of abstractions, system structure, and simulator operations. Although the designs were significantly different, this result may be influenced by some special characteristics discussed

Generational differences in factors influencing physicians to choose a work location.

INTRODUCTION: Canadian medical schools have increased enrolment and recruited more rural students in an effort to address general and rural physician shortages. The success of this approach depends on the recruitment of these newly trained physicians to under-serviced areas. Studies from North America suggest that the career expectations and practice patterns of younger, more recently graduated physicians differ from those of their older counterparts. This study explored the factors that influenced the work location choices of physicians of differing generations, who trained at universities in Saskatchewan, and Newfoundland and Labrador, two Canadian provinces with large rural populations and no community larger than 235 000 population. METHODS: Semi-structured, qualitative interviews were conducted with physicians who graduated from either the Memorial University of Newfoundland or the University of Saskatchewan. Generation definitions were based on the graduation year. Early-career physicians graduated between 1995 and 1999; mid-career physician graduated between 1985 and 1989; late-career physicians graduated between 1975 and 1979; and end-career physicians graduated between 1965 and 1969. Each physician was asked questions about the number and nature of work location changes over the course of their careers and the factors related to their decision to choose each location. Interview transcripts and notes were analyzed using a thematic analysis approach. Although the study focus was on generational differences, similarities and differences between universities, sexes and specialties (family physicians/GPs vs specialists) were also examined. Recruitment to the provinces was focused on as a whole, because the largest communities in the provinces are small compared with most urban communities. RESULTS: Forty-eight physicians were interviewed, five to nine physicians who graduated in each decade and from each university. The desire to be near family and friends was cited as the primary consideration when choosing a work location, regardless of generation. Likewise, residency training location, the ability to use their skills and knowledge fully, and the quality of recruitment efforts were important considerations in choosing a work location for all physicians. For some, remuneration was very influential in their work location decision; however, many physicians who chose to remain in their smaller 'home' provinces noted the lower cost of living in these provinces. Physicians who graduated in the 1980s and 1990s placed greater emphasis on work-life balance and spouse's employment opportunities than their older generation counterparts. In contrast, physicians who graduated in the 1960s and 1070s highlighted the medical need of the community, and the desire for adventure and to see new places as important. CONCLUSIONS: While many factors for choosing a work location appear to be stable over generations, a number of generational differences were found. Younger physicians placed greater emphasis on work-life balance and spouse's employment than older generation physicians. These differences may have important implications for small population regions which may not be able to support physician-spouse pairs or certain subspecialties. Although economic factors have largely been the focus of recruitment and retention initiatives in these provinces, the findings highlight the importance of addressing the needs and expectations of younger generation physicians in order to attract these physicians