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Why citations are not enough for open source software

A few weeks ago I wrote about why you should cite open source tools. Although I think citations important, though, there are major problems in relying on them alone to support open source work.

The biggest problem is that papers describing a software library can only give credit to the contributors at the time that the paper was written. The preferred citation for the SciPy library is “Eric Jones, Travis Oliphant, Pearu Peterson, et al”, 2001. The “et al” is not an abbreviation here, but a fixed shorthand for all other contributors. Needless to say many, many people have contributed to the SciPy library since 2001 (GitHub counts 716 contributors as of this writing), and they are unable to get credit within the academic system for those contributions. (As an aside, Google counts about 1,200 citations to SciPy, which is a breathtaking undercounting of its value and influence, and reinforces my earlier point: cite open source software! Definitely don't use this post as an excuse not to cite it!!!)

Not surprisingly, we have had massive contributions to scikit-image since our 2014 paper, and those contributors miss out on the citations to our paper.

From a maintainer point of view, one way to deal with this is to periodically write “update” publications that become the preferred way to cite the software. This is the approach taken by the CellProfiler team, for example, and the one we will take for scikit-image. This allows new contributors to benefit, while also preventing infinite returns for the original authors, which is as it should be.

I think this is as good as project maintainers can do now, but leaves open the questions of authorship, publication frequency, and the potential dilution of the authors' message.

A proper fix requires structural change that directly recognises the value of open source software to science. Software papers are in fact a hack of the academic system, a currency conversion, and as with any conversion, there are losses and inefficiencies involved. Indeed, the paper provides less value than good documentation for the software. (Last year, when someone tweeted about their latest software paper, many replies asked for the GitHub link in the abstract! People wanted to look at the software, not the paper.)

So what does open source software really need, if not citations? Of course, it's money. Citations are useful because they can potentially be translated into grants, promotions, and jobs, but wouldn't it be great if we could cut out the middleman and just have great open source translate directly into grants, promotions, and jobs?

The insane thing is that granting bodies actually give enormous amounts of money to closed source software developers, since grant money is routinely spent on software licenses. Instead of subsidising proprietary software, that money could be used to fund open source developers, and improve software for everyone.

How to fund open source

I might have left the how for a later post, but while I was drafting this, CZI announced direct funding specifically for open source software. Needless to say I think this is wonderful. I am funded by an earlier closed funding round to develop scikit-image, and I thought a lot at the time about all the other deserving, unfunded projects that I use. An open call is absolutely the right thing to do, and supporting maintenance rather than development of hot new things, as this CZI call is doing, is also the right thing to do. (Others have flagged that a single year of support, even if renewable, makes it difficult to support careers, and I agree, but this is a new space, and it makes sense that CZI would dip its toes before jmuping in.)

The response to CZI's announcement has been absolute fire. There is enormous pent-up need and frustration over funding maintenance and improvement for open source tools underpinning an enormous amount of science. (Even a month later, reading Andreas's tweet makes me want to scream in frustration in the crowded train in which I write this. Not impactful enough!?) Given the buzz around CZI's call, I wonder whether CZI has enough staff to even read through the avalanche of applications it will receive. My hope is that national funding bodies will take notice and start funding open source maintenance work, as Germany has recently done. (It's unclear to me whether Germany has repeated that call since 2016. If you know, please leave a comment below!)

Since I'm an academic, for a long time I was stuck in the mindset that granting bodies need to step up and recognise that established open source is a valuable thing to fund, and this is certainly true. More recently though, as I dipped my toes into some private sector consulting, it occurred to me that the situation is completely ridiculous — “Hey look at this incredible thing we built, it's serving thousands to millions of scientists, can we get some money to keep it going?” “It's done and it's free, why would we give you money?” It's a fundamental misunderstanding at the very top of funding agencies of how software maintenance works.

There are plenty of people that do understand the value of the software, though: its users, many of whom are in a position to use grant money to help maintain it. But open source developers have not thus far made it easy to donate money to invest in their projects. I'm not talking about a little donate button on the homepage, which will never substantially support a project. Rather, open source projects should sell a product, be it a maintenance contract, a support contract, or a new feature development, or even a feel-good contract. But “buying” an open source software package should feel exactly like buying closed-source software, and to University purchasing departments it should look exactly like a normal software purchase.

As I was thinking about this idea, I moved my blog from, for which I was paying $100 per year, to Nikola, an open source static site generator written in Python. I love Nikola, and was ready to put my $100 towards the project, but to my surprise, even a donate button was absent. As Andreas Mueller and Chris Holdgraf have pointed out, many projects haven't even considered what they would do with a large influx of money if they got one. That needs to change.

Thankfully, organizations including NumFOCUS, QuanSight, Tidelift, and others are working hard to rectify this situation. I'm trying to help where I can and I really look forward to seeing what they come up with.

If you are interested in this topic, we are organising a Birds of a Feather session to take place at the SciPy 2019 in Austin in July. Please join us!


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