Evidence-based SE groups doing interesting work, 2021 version

Who are the research groups currently doing interesting work in evidenced-base software engineering (academics often use the term empirical software engineering)? Interestingness is very subjective, in my case it is based on whether I think the work looks like it might contribute something towards software engineering practices (rather than measuring something to get a paper published or fulfil a requirement for an MSc or PhD). I last addressed this question in 2013, and things have changed a lot since then.

This post focuses on groups (i.e., multiple active researchers), and by “currently doing” I’m looking for multiple papers published per year in the last few years.

As regular readers will know, I think that clueless button pushing (a.k.a. machine learning) in software engineering is mostly fake research. I tend to ignore groups that are heavily clueless button pushing oriented.

Like software development groups, research groups come and go, with a few persisting for many years. People change jobs, move into management, start companies based on their research, new productive people appear, and there is the perennial issue of funding. A year from now, any of the following groups may be disbanded or moved on to other research areas.

Some researchers leave a group to set up their own group (even moving continents), and I know that many people in the 2013 survey have done this (many in the Microsoft group listed in 2013 are now scattered across the country). Most academic research is done by students studying for a PhD, and the money needed to pay for these students comes from research grants. Some researchers are willing to spend their time applying for grants to build a group (on average, around 40% of a group’s lead researcher’s time is spent applying for grants), while others are happy to operate on a smaller scale.

Evidence-based research has become mainstream in software engineering, but this is not to say that the findings or data have any use outside of getting a paper published. A popular tactic employed by PhD students appears to be to look for what they consider to be an interesting pattern in code appearing on Github, and write a thesis that associated this pattern with an issue thought to be of general interest, e.g., predicting estimates/faults/maintainability/etc. Every now and again, a gold nugget turns up in the stream of fake research.

Data is being made available via personal Github pages, figshare, osf, Zenondo, and project or personal University (generally not a good idea, because the pages often go away when the researcher leaves). There is no current systematic attempt to catalogue the data.

There has been a huge increase in papers coming out of Brazil, and Brazilians working in research groups around the world, since 2013. No major Brazilian name springs to mind, but that may be because I have not noticed that they are Brazilian (every major research group seems to have one, and many of the minor ones as well). I may have failed to list a group because their group page is years out of date, which may be COVID related, bureaucracy, or they are no longer active.

The China list is incomplete. There are Chinese research groups whose group page is hosted on Github, and I have failed to remember that they are based in China. Also, Chinese pages can appear inactive for a year or two, and then suddenly be updated with lots of recent information. I have not attempted to keep track of Chinese research groups.

Organized by country, groups include (when there is no group page available, I have used the principle’s page, and when that is not available I have used a group member page; some groups make no attempt to help others find out about their work):

Belgium (I cite the researchers with links to pdfs)

Brazil (Garcia, Steinmacher)

Canada (Antoniol, Data-driven Analysis of Software Lab, Godfrey and Ptidel, Robillard, SAIL; three were listed in 2013)

China (Lin Chen, Lu Zhang)

Germany (Chair of Software Engineering, CSE working group, Software Engineering for Distributed Systems Group, Research group Zeller)

Greece (listed in 2013)

Israel

Italy (listed in 2013)

Japan (Inoue lab, Kamei Web, Kula, and Kusumoto lab)

Netherlands

Spain (the only member of the group listed in 2013 with a usable web page)

Sweden (Chalmers, KTH {Baudry and Monperrus, with no group page})

Switzerland (SCG and REVEAL; both listed in 2013)

UK

USA (Devanbu, Foster, Maletic, Microsoft, PLUM lab, SEMERU, squaresLab, Weimer; two were listed in 2013)

Sitting here typing away, I have probably missed out some obvious candidates (particularly in the US). Suggestions for omissions welcome (remember, this is about groups, not individuals).

GDPR has a huge impact on empirical software engineering research

The EU’s General Data Protection Regulation (GDPR) is going to have a huge impact on empirical software engineering research. After 25 May 2018, analyzing source code will never be the same again.

I am not a lawyer and nothing qualifies me to talk about the GDPR.

People put their name in source code, bug tracking databases and discussion forums; this is personal identifying information.

Researchers use personal names to obtain information about a wide variety of activities, e.g., how much code did individuals write, how many bug reports did they process, contributions in discussions of one sort or another.

Open source licenses give others all kinds of rights (e.g., ability to use and modify source code), but they do not contain any provisions for processing personal data.

Adding a “I hereby give permission for anybody to process information about my name in any way they see fit.” clause to licenses is not going to help.

The GDPR requires (article 5: Principles relating to processing of personal data):

“Personal data shall be: … collected for specified, explicit and legitimate purposes and not further processed in a manner that is incompatible with those purposes;”

That is, personal data can only be processed for the specific reason it was collected, i.e., if you come up with another bright idea for analysis of data that has just been collected, it may be necessary to obtain consent, from those whose personal data it is, before trying out the bright idea.

It is not possible to obtain blanket permission (article 6, Lawfulness of processing):

“…the data subject has given consent to the processing of his or her personal data for one or more specific purposes;”, i.e., consent has to be obtained from the data subject for each specific purpose.

Github’s Global Privacy Practices shows that Github are intent on meeting the GDPR requirements, they include: “GitHub provides clear methods of unambiguous, informed consent at the time of data collection, when we do collect your personal data.”. Processing personal information, about an EU citizen, contained in source code appears to be a violation of Github’s terms of service.

The GDPR has many other requirements, e.g., right to obtain information on what information is held and right to be forgotten. But, the upfront killer is not being able to cheaply collect lots of code and then use personal information to help with the analysis.

There are exceptions for: Processing for archiving, scientific or historical research or statistical purposes. Can somebody who blogs and is writing a book claim to be doing scientific research? People who know more about these exceptions than me, tell me that there could be a fair amount of paperwork involved when making use of the exception, i.e., being able to show that privacy safeguards are in place.

Then, there is the issue of what constitutes personal information. Git’s hashing algorithm makes use of the committer’s name and/or email address. Is a git hash personal identifying information?

A good introduction to the GDPR for developers.

Almost all published analysis of fault data is worthless

Faults are the subject of more published papers that any other subject in empirical software engineering. Unfortunately, over 98.5% of these fault related papers are at best worthless and at worst harmful, i.e., make recommendations whose impact may increase the number of faults.

The reason most fault papers are worthless is the data they use and the data they don’t to use.

The data used

Data on faults in programs used to be hard to obtain, a friend in a company that maintained a fault database was needed. Open source changed this. Now public fault tracking systems are available containing tens, or even hundreds, of thousands of reported faults. Anybody can report a fault, and unfortunately anybody does; there is a lot of noise mixed in with the signal. One study found 43% of reported faults were enhancement requests, the same underlying fault is reported multiple times (most eventually get marked as duplicate, at the cost of much wasted time) and …

Fault tracking systems don’t always contain all known faults. One study found that the really important faults are handled via email discussion lists, i.e., they are important enough to require involving people directly.

Other problems with fault data include: biased reported of problems, reported problem caused by a fault in a third-party library, and reported problem being intermittent or not reproducible.

Data cleaning is the essential first step that many of those who analyze fault data fail to perform.

The data not used

Users cause faults, i.e., if nobody ever used the software, no faults would be reported. This statement is as accurate as saying: “Source code causes faults”.

Reported faults are the result of software being used with a set of inputs that causes the execution of some sequence of tokens in the source code to have an effect that was not intended.

The number and kind of reported faults in a program depends on the variety of the input and the number of faults in the code.

Most fault related studies do not include any user related usage data in their analysis (the few that do really stand out from the crowd), which can lead to very wrong conclusions being drawn.

User usage data is very hard to obtain, but without it many kinds of evidence-based fault analysis are doomed to fail (giving completely misleading answers).