Monday, May 18, 2009

ICSE 09 - Day Three

Andreas Zeller, professor at Saarland University in Germany, apart from being on of the nicest people I've met so far this week, also had some very positive feedback on my research idea. He agreed with it's principle, and that research in this area would be valid. One of his first questions after I finished presenting my idea was about incentive for participation. I thought he was asking about how we would convince students and pros to give up their time to participate in our study, but this wasn't the case. he recounted results found at Saarland when teaching students to test their code. Traditional methods obviously didn't work effectively, so they switched tracks. Student assignments were assigned with a spec and a suite of unit tests that the students could use to validate their work as they progressed. Once nightly a second set of tests were run by the instructor, the source of which was kept secret, and the students were informed in the morning of the number of tests they passed and failed. To grade the assignment, a third set of (secret) tests were run. Students begin with a mark of 100%. The first failing test reduces their mark to 80%. The second, to 70%. The third to 60%. The grading continues in a similarly harsh fashion. The first assignment in the course is almost universally failed, as students drastically underestimate how thorough they need to be with their tests. Subsequent assignments are much better, and the students focus strongly on testing, and indeed collaborate by sharing test cases and testing each others assignments to eliminate as many errors as possible before the submission date. Once the students have the proper motivation to test, they eagerly consume any instruction in effective testing techniques. Andreas found that simple instruction in JUnit and maybe TDD was all that was required, and the rest the students figured out for themselves. This type of self-directed learning is encouraging, but the whole situation makes me think that these students may be working harder, but not smarter, to test their software. It may be possible that by providing instruction not only in the simple operation of an XUnit framework, but also in things like effective test case selection, they may be able to reach similar test coverage or defect discovery rates, while expending less frantic effort.
Thought: drop the first assignment from the course's final mark, as it is not used for evaluation as much as it is a learning experience (of course, don't tell the students this, otherwise the important motivational lesson will be lost).
In addition to this, Andreas, just as other folks I've spoken to so far, emphasized the need to keep my study narrowly focused on a single issue, as well as controlling the situation in a way that enables precise measurements to be made both before and after implementing the curriculum changes we hope to elicit from the study, to accurately determine the improvements (if any exist). I am beginning to see a loose correlation between a researcher's viewpoint regarding empiricism in SE research (positivist on the right and constructivist on the left) and their amount of emphasis on narrowness of focus. Often times, those people who advocate exploratory qualitative studies also recommend wider bands of observation while conducting these studies. This is likely an over generalization, and I apologize in advance to anyone who may disagree with this.

1 comment:

catenary said...

It's a simple generalization, but it's fair: case study research according to Yin, for instance, is effective when you have many more variables than cases to observe; the opposite is true of controlled experiments.

How do you find the energy to blog after a full day of conferencing though? I just can't get myself to it.