Join a crowdsourced search for software engineering data

Software engineering data, that can be made publicly available, is very rare; most people don’t attempt to collect data, and when data is collected, people rarely make any attempt to hang onto the data they do collect.

Having just one person actively searching for software engineering data (i.e., me) restricts potential sources of data to be English speaking and to a subset of development ecosystems.

This post is my attempt to start a crowdsourced campaign to search for software engineering data.

Finding data is about finding the people who have the data and have the authority to make it available (no hacking into websites).

Who might have software engineering data?

In the past, I have emailed chief technology officers at companies with less than 100 employees (larger companies have lawyers who introduce serious amounts of friction into releasing company data), and this last week I have been targeting Agile coaches. For my evidence-based software engineering book I mostly emailed the authors of data driven papers.

A lot of software is developed in India, China, South America, Russia, and Europe; unless these developers are active in the English-speaking world, I don’t see them.

If you work in one of these regions, you can help locate data by finding people who might have software engineering data.

If you want to be actively involved, you can email possible sources directly, alternatively I can email them.

If you want to be actively involved in the data analysis, you can work on the analysis yourself, or we can do it together, or I am happy to do it.

In the English-speaking development ecosystems, my connection to the various embedded ecosystems is limited. The embedded ecosystems are huge, there must be software data waiting to be found. If you are active within an embedded ecosystem, you can help locate data by finding people who might have software engineering data.

The email template I use for emailing people is below. The introduction is intended to create a connection with their interests, followed by a brief summary of my interest, examples of previous analysis, and the link to my book to show the depth of my interest.

By all means cut and paste this template, or create one that you feel is likely to work better in your environment. If you have a blog or Twitter feed, then tell them about it and why you think that evidence-based software engineering is important.

Be responsible and only email people who appear to have an interest in applying data analysis to software engineering. Don’t spam entire development groups, but pick the person most likely to be in a position to give a positive response.

This is a search for gold nuggets, and the response rate will be very low; a 10% rate of reply, saying sorry not data, would be better than what I get. I don’t have enough data to be able to calculate a percentage, but a ballpark figure is that 1% of emails might result in data.

I treat the search as a background task, taking months to locate and email, say, 100-people considered worth sending a targeted email. My experience is that I come up with a search idea or encounter a blog post that suggests a line of enquiry, that may result in sending half-a-dozen emails. The following week, if I’m lucky, the same thing might happen again (perhaps with fewer emails). It’s a slow process.

If people want to keep a record of ideas tried, the evidence-based software engineering Slack channel could do with some activity.

Hello,

A personalized introduction, such as: I have been reading
your blog posts on XXX, your tweets about YYY,
your youtube video on ZZZ.

My interest is in trying to figure out the human issues
driving the software process.

Here are two detailed analysis of Agile estimation data:
https://arxiv.org/abs/1901.01621
and
https://arxiv.org/abs/2106.03679

My book Evidence-based Software Engineering discusses what is
currently known about software engineering, based on an
analysis of all the publicly available data.
pdf+code+all data freely available here:
http://knosof.co.uk/ESEUR/

and I'm always on the lookout for more software data.
This email is a fishing request for software engineering data.

I offer a free analysis of software data, provided an
anonymised version of the data can be made public.

Fishing for software data

During 2021 I sent around 100 emails whose first line started something like: “I have been reading your interesting blog post…”, followed by some background information, and then a request for software engineering data. Sometimes the request for data was specific (e.g., the data associated with the blog post), and sometimes it was a general request for any data they might have.

So far, these 100 email requests have produced one two datasets. Around 80% failed to elicit a reply, compared to a 32% no reply for authors of published papers. Perhaps they don’t have any data, and don’t think a reply is worth the trouble. Perhaps they have some data, but it would be a hassle to get into a shippable state (I like this idea because it means that at least some people have data). Or perhaps they don’t understand why anybody would be interested in data and must be an odd-ball, and not somebody they want to engage with (I may well be odd, but I don’t bite :-).

Some of those who reply, that they don’t have any data, tell me that they don’t understand why I might be interested in data. Over my entire professional career, in many other contexts, I have often encountered surprise that data driven problem-solving increases the likelihood of reaching a workable solution. The seat of the pants approach to problem-solving is endemic within software engineering.

Others ask what kind of data I am interested in. My reply is that I am interested in human software engineering data, pointing out that lots of Open source is readily available, but that data relating to the human factors underpinning software development is much harder to find. I point them at my evidence-based book for examples of human centric software data.

In business, my experience is that people sometimes get in touch years after hearing me speak, or reading something I wrote, to talk about possible work. I am optimistic that the same will happen through my requests for data, i.e., somebody I emailed will encounter some data and think of me 🙂

What is different about 2021 is that I have been more willing to fail, and not just asking for data when I encounter somebody who obviously has data. That is to say, my expectation threshold for asking is lower than previous years, i.e., I am more willing to spend a few minutes crafting a targeted email on what appear to be tenuous cases (based on past experience).

In 2022 I plan to be even more active, in particular, by giving talks and attending lots of meetups (London based). If your company is looking for somebody to give an in-person lunchtime talk, feel free to contact me about possible topics (I’m always after feedback on my analysis of existing data, and will take a 10-second appeal for more data).

Software data is not commonly available because most people don’t collect data, and when data is collected, no thought is given to hanging onto it. At the moment, I don’t think it is possible to incentivize people to collect data (i.e., no saleable benefit to offset the cost of collecting it), but once collected the cost of hanging onto data is peanuts. So as well as asking for data, I also plan to sell the idea of hanging onto any data that is collected.

Fishing tips for software data welcome.

Learning useful stuff from the Reliability chapter of my book

What useful, practical things might professional software developers learn from my evidence-based software engineering book?

Once the book is officially released I need to have good answers to this question (saying: “Well, I decided to collect all the publicly available software engineering data and say something about it”, is not going to motivate people to read the book).

This week I checked the reliability chapter; what useful things did I learn (combined with everything I learned during all the other weeks spent working on this chapter)?

A casual reader skimming the chapter would conclude that little was known about software reliability, and they would be right (I already knew this, but I learned that we know even less than I thought was known), and many researchers continue to dig in unproductive holes.

A reader with some familiarity with reliability research would be surprised to see that some ‘major’ topics are not discussed.

The train wreck that is machine learning has been avoided (not forgetting that the data used is mostly worthless), mutation testing gets mentioned because of some interesting data (the underlying problem is that mutation testing assumes that coding mistakes are local to one line, but in practice coding mistakes often involve multiple lines), and the theory discussions don’t mention non-homogeneous Poisson process as the basis for software fault models (because this process is not capable of solving the questions asked).

What did I learn? My highlights include:

  • Anne Choa‘s work on population estimation. The takeaway from this work is that if people want to estimate the number of remaining fault experiences, based on previous experienced faults, then every occurrence (i.e., not just the first) of a fault needs to be counted,
  • Janet Dunham’s top read work on software testing,
  • the variability in the numeric percentage that people assign to probability terms (e.g., almost all, likely, unlikely) is much wider than I would have thought,
  • the impact of the distribution of input values on fault experiences may be detectable,
  • really a lowlight, but there is a lot less publicly available data than I had expected (for the other chapters there was more data than I had expected).

The last decade has seen fuzzing grow to dominate the headlines around software reliability and testing, and provide data for people who write evidence-based books. I don’t have much of a feel for how widely used it is in industry, but it is a very useful tool for reliability researchers.

Readers might have a completely different learning experience from reading the reliability chapter. What useful things did you learn from the reliability chapter?

The dark-age of software engineering research: some evidence

Looking back, the 1970s appear to be a golden age of software engineering research, with the following decades being the dark ages (i.e., vanity research promoted by ego and bluster), from which we are slowly emerging (a rough timeline).

Lots of evidence-based software engineering research was done in the 1970s, relative to the number of papers published, and I have previously written about the quantity of research done at Rome and the rise of ego and bluster after its fall (Air Force officers studying for a Master’s degree publish as much software engineering data as software engineering academics combined during the 1970s and the next two decades).

What is the evidence for a software engineering research dark ages, starting in the 1980s?

One indicator is the extent to which ancient books are still venerated, and the wisdom of the ancients is still regularly cited.

I claim that my evidence-based software engineering book contains all the useful publicly available software engineering data. The plot below shows the number of papers cited (green) and data available (red), per year; with fitted exponential regression models, and a piecewise regression fit to the data (blue) (code+data).

Count of papers cited and data available, per year.

The citations+date include works that are not written by people involved in software engineering research, e.g., psychology, economics and ecology. For the time being I’m assuming that these non-software engineering researchers contribute a fixed percentage per year (the BibTeX file is available if anybody wants to do the break-down)

The two straight line fits are roughly parallel, and show an exponential growth over the years.

The piecewise regression (blue, loess was used) shows that the rate of growth in research data leveled-off in the late 1970s and only started to pick up again in the 1990s.

The dip in counts during the last few years is likely to be the result of me not having yet located all the recent empirical research.