Fundamental Laws and Assumptions of Software Maintenance

Researchers must pay far more attention to discovering and validating the principles that underlie software maintenance and evolution. This was one of the major conclusions reached during the International Workshop on Empirical Studies of Software Maintenance. This workship, held in November 1996 in Monterey, California, brought together an international group of researchers to discuss the successes, challenges and open issues in software maintenance and evolution. This article documents the discussion of the subgroup on fundamental laws and assumption of software maintenance. The participants of this group in included researchers in software engineering, the behavioral sciences, information systems and statistics. Their main conclusion was that insufficient effort has been paid to synthesizing research conjectures into validated theories and this problem has slowed progress in software maintenance. To help remedy this situation they made the following recommendations: (1) when we use empirical methods, an explicit goal should be to develop theories, (2) we should look to other disciplines for help where it is appropriate, and (3) our studies should use a wider range of empirical methods (Also cross-referenced as UMIACS-TR-97-21

Upgrading High School Math: A Look at Three Transition Courses

This issue of CPRE Policy Briefs focuses on the nature of instruction in transition math courses, the consequences of student placement in the new transition courses, and the linkages among course type, course content, and student achievement. The findings presented here are based on both qualitative and quantitative data gathered from seven high school across four districts in two states. We studied transition math courses in seven high schools in San Diego and San Francisco in California and in Buffalo and Rochester in New York. We chose schools that had high percentages of minority and low-income students, because the problem of dead-end classes for low-achieving students is most sever in such schools. The transition math courses were initiated as early as 10 years ago in Rochester, New York schools, and 3 to 5 years ago in California schools

Relatedness and Population Differentiation in a Colonial Butterfly, Eucheira socialis (Lepidoptera: Pieridae)

Eucheira socialis (Westwood) occurs above 1,800 m in mountains throughout Mexico and has a remarkable suite of autapomorphies, including communal larval nests and a mean primary sex ratio of 70% males. We gathered allozyme data for 31 loci from individuals within nests within populations and used hierarchical F statistics to assess population structure and relatedness at these levels. Allozyme variation was far lower than reported in most Lepidoptera, and was absent from the populations sampled from southern Mexico. Among 5 sample sites distributed throughout Mexico, differentiation was high (FST = 0.54), which is consistent with a history of interrupted gene flow. At lower hierarchical levels in the variable populations, we found significant excess heterozygotes within nests (FIN = −0.15) and evidence for structuring within subpopulations (FIS =0.015, significantly greater than FIN). Average relatedness among nestmates was rNS = 0.28, which is significantly less than r = 0.5. This is probably caused largely by interchange among nests on multinest trees. ADAM H. PORTE

A Review of Software Inspections

For two decades, software inspections have proven effective for detecting defects in software. We have reviewed the different ways software inspections are done, created a taxonomy of inspection methods, and examined claims about the cost-effectiveness of different methods. We detect a disturbing pattern in the evaluation of inspection methods. Although there is universal agreement on the effectiveness of software inspection, their economics are uncertain. Our examination of several empirical studies leads us to conclude that the benefits of inspections are often overstated and the costs (especially for large software developments) are understated. Furthermore, some of the most influential studies establishing these costs and benefits are 20 years old now, which leads us to question their relevance to today's software development processes. Extensive work is needed to determine exactly how, why, and when software inspections work, and whether some defect detection techniques might be more cost-effective than others. In this article we ask some questions about measuring effectiveness of software inspections and determining how much they really cost when their effect on the rest of the development process is considered. Finding answers to these questions will enable us to improve the efficiency of software development. (Also cross-referenced as UMIACS-TR-95-104

An Experiment to Assess the Cost-Benefits of Code Inspections in Large Scale Software Development

We are conducting a long-term experiment (in progress) to compare the costs and benefits of several different software inspection methods. These methods are being applied by professional developers to a commercial software product they are currently writing. Because the laboratory for this experiment is a live development effort, we took special care to minimize cost and risk to the project, while maximizing our ability to gather useful data. This article has several goals: (1) to describe the experiment's design and show how we used simulation techniques to optimize it, (2) to present our preliminary results and discuss their implications for both software practitioners and researchers, and (3) to discuss how we expect to modify the experiment in order to reduce potential risks to the project. For each inspection we randomly assign 3 independent variables: (1) the number of reviewers on each inspection team (1, 2 or 4), (2) the number of teams inspecting the code unit (1 or 2), and (3) the requirement that defects be repaired between the first and second team's inspections. The reviewers for each inspection are randomly selected without replacement from a pool of 11 experienced software developers. The dependent variables for each inspection include inspection interval (elapsed time), total effort, and the defect detection rate. To date we have completed 34 of the planned 64 inspections. Our preliminary results challenge certain long-held beliefs about the most cost-effective ways to conduct inspections and raise some questions about the feasibility of recently proposed methods. (Also cross-referenced as UMIACS-TR-95-14

Comparing Detection Methods for Software Requirements Inspections: A Replicated Experiment

(Also cross-referenced as UMIACS-TR-94-93

Understanding the Sources of Variation in Software Inspections

In a previous experiment, we determined how various changes in three structural elements of the software inspection process (team size, and number and sequencing of session), altered effectiveness and interval. our results showed that such changes did not significantly influence the defect detection reate, but that certain combinations of changes dramatically increased the inspection interval. We also observed a large amount of unexplained variance in the data, indicating that other factors much be affecting inspection performance. The nature and extent of these other factos now have to be determined to ensure that they had not biased our earlier results. Also, identifying these other factors might suggest additional ways to improve the efficiency of inspection. Acting on the hypothesis that the "inputs" into the inspection process (reviewers, authors, and code units) were significant sources of variation, we modeled their effects on inspection performance. We found that they were responsible for much more variation in defect detection than was process structure. This leads us to conclude that better defect detection techniques, not better process structures, at the key to improving inspection effectiveness. The combined effects of process inputs and process structure on the inspection interval accounted for only a small percentage of the variance in inspection interval. Therefore, there still remain other factors which need to be identified. (Also cross-referenced as UMIACS-TR-97-22

Development of a High-Throughput Assay for Identifying Inhibitors of TBK1 and IKKε

IKKε and TBK1 are noncanonical IKK family members which regulate inflammatory signaling pathways and also play important roles in oncogenesis. However, few inhibitors of these kinases have been identified. While the substrate specificity of IKKε has recently been described, the substrate specificity of TBK1 is unknown, hindering the development of high-throughput screening technologies for inhibitor identification. Here, we describe the optimal substrate phosphorylation motif for TBK1, and show that it is identical to the phosphorylation motif previously described for IKKε. This information enabled the design of an optimal TBK1/IKKε substrate peptide amenable to high-throughput screening and we assayed a 6,006 compound library that included 4,727 kinase-focused compounds to discover in vitro inhibitors of TBK1 and IKKε. 227 compounds in this library inhibited TBK1 at a concentration of 10 µM, while 57 compounds inhibited IKKε. Together, these data describe a new high-throughput screening assay which will facilitate the discovery of small molecule TBK1/IKKε inhibitors possessing therapeutic potential for both inflammatory diseases and cancer