Murphy, Christian
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Publication An Empirical Study of Off-by-one Loop Mutation(2015-07-31) Raunak, M. S.; Murphy, Christian; O'Haver, BryanContext: Developing test cases that are measurably effective in finding faults in programs is a very challenging research problem. Mutation testing, a prominent technique developed to address this challenge, often becomes com- putationally too expensive for practical use due to the very large number of mutants that need to be analyzed. Objective: This paper evaluates the impact of One-by-one (OBO) loop mutation in reducing the cost of mutation analysis and investigates this technique's effectiveness in measuring the strength or weakness of test suites. Method: A set of Java and C programs have been used to generate both OBO and traditional mutants. Mutation scores are computed and analyzed for both sets of mutants. An analysis of first order vs. higher order loop mutations have also been performed. Results: On average, 89.15% fewer mutants are generated by OBO op- erator in comparison to traditional operators while the two sets of muta- tion scores still remain highly positively correlated (correlation coefficient of .9228) indicating the usefulness of OBO operator in measuring test suite's ef- fectiveness of finding faults in programs. We also investigate the relationship between first order OBO mutation (FOM) and their corresponding higher order mutations (HOM). We have found that OBO HOMs do not subsume their corresponding FOMs. Conclusion: We conclude that One-by-one (OBO) loop mutant operator, which targets specific program elements for mutation, can greatly reduce the number of mutants generated, and thus make the mutation analysis relatively inexpensive and practical while still being capable of providing useful measurement of the strength or weakness of a test suite. Our investigation into the relationship between higher order OBO mutants (HOM) and first order OBO mutants (FOM) has revealed that OBO HOMs usually do not add any value to the mutation analysis over the corresponding FOMs.Publication Is a Rigorous Agile Methodology the Best Development Strategy for Small Scale Tech Startups?(2013-01-01) Yau, Alex; Murphy, ChristianRecently, Agile development processes have become popular in the software development community, and have been shown to be effective in large organizations. However, given that the communication and cooperation dynamics in startup companies are very different from that of larger, more established companies, and the fact that the initial focus of a startup might be significantly different from its ultimate goal, it is questionable whether a rigid process model that works for larger companies is appropriate in tackling the problems faced by a startup. When we scale down even further and observe the small scale startup with only a few members, many of the same problems that Agile methodology sets out to solve do not even exist. Then, for a small scale startup, is it still worth putting the resources into establishing a process model? Do the benefits of adopting an Agile methodology outweigh the opportunity cost of spending the resources elsewhere? This paper examines the advantages and disadvantages of adopting an Agile methodology in a small scale tech startup and compares it to other process models, such as the Waterfall model and Lean Startup. In determining whether a rigorous agile methodology is the best development strategy for small scale tech startups, we consider the metrics of cost, time, quality, and scope in light of the particular needs of small startup organizations, and present a case study of a company that has needed to answer this very question.Publication Emerging Scholars Program—A PLTL-CS Program That Increases Recruitment and Retention of Women in the Major(2012-01-01) Powell, Rita M; Murphy, Christian; Cannon, Adam; Gordon, Joshua; Ramachandran, ArthiThe Emerging Scholars Program (ESP) in Computer Science is a Peer Led Team Learning (PLTL) approach to bringing undergraduates new to the discipline together with peer mentors to work on computational problems, and to expose them to the broad array of disciplines within computer science. This program demonstrates that computer science is necessarily a collaborative activity that focuses more on problem solving and algorithmic thinking than on programming. In spring 2012 the computer science department at an urban research university university completed the 9th iteration of ESP, with 104 women and 36 men completing the program. Our evaluation data indicates that ESP increased enrollment in the computer science major. 47% of students who took ESP along with the introduction to computer programming course at the university study site during this study majored in computer science. In addition, survey results indicated that a large majority of students intended to take another computer science course, were enthusiastic about the program, and found the workshop topics exciting and engaging. Participants reported that they learned more about computer science in ESP, and would recommend ESP to others.Publication Lessons Learned from a PLTL-CS Program(2011-01-01) Murphy, Christian; Powell, Rita; Parton, Kristen; Cannon, AdamThe Peer-Led Team Learning (PLTL) approach has previously been shown to be effective in recruiting and retaining students, particularly under-represented students, in undergraduate introductory CS courses. In PLTL, small groups of students are led by an undergraduate peer and work together to solve problems related to CS. At Columbia University, the Columbia Emerging Scholars Program has used PLTL in an effort to increase enrollment in CS courses beyond the introductory level, and to increase the number of students who select Computer Science as their major, by demonstrating that CS is necessarily a collaborative activity that focuses more on problem solving and algorithmic thinking than on programming. Over the past five semesters, 68 students have completed the program, and preliminary results indicate that this program has had a positive effect on increasing participation in the major. This paper discusses our experiences of building and expanding the Columbia Emerging Scholars program, and addresses such topics as recruiting, training, scheduling, student behavior, and evaluation. We expect that this paper will provide a valuable set of lessons learned to other educators who seek to launch or grow a PLTL program at their institution as well.