Community Data Science Collective

This post is about my (Nathan TeBlunthuis) paper (pdf) just published at ICWSM 2025.

Often, several different online communities exist where similar people talk about similar things. This is really easy to observe from browsing platforms like Reddit or Facebook groups.

For example, as we can see from this visualization of clustered subreddits with overlapping users, there are many different subreddits related to cycling. We see some communities have different emphases in complementary ways like “fixedgearbicycle” and “bicycletouring” — these are different types of cycling. But why have a community for
“cycling” and a different one for “bicycling”? A number of puzzles appear when we reflect on the existence of such related communities.

How do online communities relate to each other?

Why not have one large community that does everything?

How do people construct these systems of related online communities?

I investigated these questions in my dissertation using the theoretical lens of organizational ecology drawn from organizational sociology. This new paper explored some findings from earlier projects in more depth. The paper I published in ICWSM 2022 (pdf), takes up the question of ecological relationships among online communities. I used time series models to infer networks of competition and mutualism between overlapping online communities. This work found evidence that they tended to be mutualistic. For example, the diagram below shows a network of mental health subreddits that is dense with mutualism.

However, this method, based on vector autoregression (VAR) models of activity, assumes that these relationships are static and constant over time. But dynamics of attention online are often bursty, and online communities grow, decline, and change over time in other ways. So, in this new work, I adopted nonlinear models called (regularized) S-map that can model more complex dynamics.

Since I found in the previous work that mutualism tended to happen more often than competition, I wanted to find out if that result was robust using the S-map. Since the S-map breaks these relationships down into episodes of competition or mutualism it afforded testing a more nuanced hypothesis about this tendency towards mutualism.

H1: Mutualistic interactions will be more frequent and longer lasting than competitive interactions.

In the another empirical paper previously published at CSCW 2022 (acm dl), we focused on the question of why people build overlapping online communities and found that they complementary sets of benefits to members, as illustrated below. Trade-offs between the benefits lead to specialized roles for different types of communities.

This reflects propositions from ecology that specialization can be a strategy to avoid competition. The new study seeks to provide more generalizable quantitative evidence about how online communities find their specialized niches. Ecology theory suggests that online communities, similar to organizations or organisms, might adapt to increase specialization and thereby promote more mutualistic relationships. To investigate whether people build specialized online communities through such an adaptive feedback process, I set out to test the following two hypotheses:

H2: Two communities having greater competition (mutualism) will subsequently have greater decreases (increases) in overlap.

H3: Two subreddits having decreasing (increasing) overlap will subsequently have greater mutualism (competition).

Methods and measures

To test these three hypotheses, I had to measure competition/mutualism, and overlap within clusters of related subreddits over time. I made topic- and user-overlap measures based on a community embedding via the LSA algorithm. To create the clusters I reused the approach from the earlier paper by using the HDBSCAN algorithm based on user overlap. As mentioned above I used the Regularized S-MAP algorithm to create a dynamic measure of ecological influence. With these longitudinal measures in hand I could test the hypotheses using two-way fixed-effects panel data estimators with dyad-robust standard errors. That’s a brief and dense summary of the methods. The chart below might help you make sense of it, but if you care to fully understand you’ll want to check out the full paper.

Here are a few final notes on the data and methods. The data came from the Pushshift Reddit archive of submissions and comments from December 5^th 2015 to April 13^th 2020. I Started with the 19,533 subreddits that were active during at least 20% of study period weeks, excluding NSFW subreddits. HDBSCAN clustering discovered related 1,919 clusters of 8,806 subreddits having 48,484 relationships measured 17,374,116 times over 758 weeks.

Results

I found support for H1, which predicted that mutualistic interactions will be more frequent and longer lasting than competitive interactions. The plot below shows evidence in favor of the hypothesis. First, we can see clearly that the longest episodes tend to be mutualistic.
Notably, these ecological relationships are often bursty and short-lived. The average length of a mutualistic episode was 2.13 weeks and the average length of a competitive episode was just 1.83 weeks.

I also found support for H2, which predicted that I’d find positive coefficients for previous ecological interaction indicating that competition predicts decreases in overlap. Indeed, the panel regression models found that online communities tend to increase their specialization a bit in relatively competitive conditions, by about 0.02 standard deviations in term or user overlap for every 1-unit increase in competition.

Do increasingly specialized communities tend to decrease their competition as predicted by H3? My analysis didn’t find evidence for this. In fact, according to the panel regression models, after specialization increases, competition actually tends to increase as well.

Discussion

What to take away from all this? I still think the most important finding from this work to me is the robustness of the tendency toward mutualism among online communities. Unlike firms or other organizations that demand relatively exclusive commitments from their members, it is easy to participate in many online communities. Where classical organizations (imagine firms, churches, sports teams, nonprofit, and state organizations) seem likely to compete over employees, customers, or members online communities seem to benefit to some extant from sharing users with each other. I suspect this has to do with the ease with which nonrival content, ideas, and knowledge move between communities.

A second important takeaway from this work is that I think the evidence it finds for the adaptation explanation for the tendency toward mutualism isn’t all that convincing. Sure, communities in competition tend to become more specialized, but the effect size is pretty small and the fact that specialization doesn’t reduce competition suggests that it isn’t truly adaptive in the strongest sense. Put another way, specialized online communities might be made via an adaptive process, or they might be born out of the intentions and designs of their founders and early joiners. This work finds a bit of evidence for how specialization might be made, but the born process merits more investigation.

One clue about the significance of design for specialization comes from fellow CDSC-er Jeremy Foote‘s a nice CHI paper (acm dl) last year on how the early stages of a subreddit’s development are important to its trajectory and found that most subreddit creators didn’t set out to create a large community. Another study (arxiv.org), by Chenhao Tan on “community genealogy” shows how the growth of new subreddits often seems to depend on having high overlap with a “parent” subreddit. These papers don’t focus on specialization, but it would be cool to see future work take up these ideas.

If you enjoyed reading this summary or want to learn more, please check out the full paper. I got the chance to speculate a bit about what sorts of future technology designs might assist community leaders in crafting online communities to fill ecological roles. I also got to engage with ecological theory in a new way writing this. I hope you read and enjoy.

Finally, I wasn’t able to attend ICWSM in person this year, so I want to thank Kristen Engel for presenting on my behalf. I also want to note that CDSC-er Kaylea Champion and I were both recognized as “best reviewers” at the conference.

This work started as a chapter of my dissertation. Thanks to the committee — Professors Benjamin Mako Hill, Kirsten Foot, Aaron Shaw, David McDonald and Emma Spiro.

I also gratefully acknowledge support by NSF grants IIS-1908850 and IIS-1910202 and GRFP \#2016220885. This work was facilitated through the use of the advanced computational infrastructure provided by the Hyak supercomputer system at the University of Washington and TACC at the University of Texas.

A number of our CDSC folks will be attending the 75th Annual International Communication Association Conference “Disrupting and Consolidating Communication Research” in Denver, Colorado from June 12th to June 16th this year.

Below, you can find the schedule of where our CDSC members will be:

Friday

10:30 – 11:45, HIGH-DENSITY: Advances and Best Practices in Text Classification: Computational Methods. Centennial A (Regency 3)  (Benjamin Mako Hill will be the Session Chair)

13:30 – 14:45, Political Communication Poster Session: Political Communication. “The Politics of the Non-Political: A Scoping Review (2004–2024)” by Yufan Guo, Chinese U of Hong Kong, and Yibin Fan, University of Washington

13:30 – 14:45, HIGH-DENSITY: GIFTS in Instructional and Developmental Communication:  Instructional and Developmental Communication.  “Welcome Aboard: Simulating an Outsider-Within’s Organizational Assimilation and Socialization Through Role-Play” by Mavis Akom, Purdue U, Haley Sawyer, Purdue U, Loizos Bitsikokos, Purdue U, Alyssa Reed, Purdue U, Favour Ojike, Purdue U, Pamela Boateng, Purdue U, Onyinyechi Beatrice, Purdue U, Inusah Mohammed, Purdue U, Seungyoon Lee, Purdue U

Saturday

15:00 PM – 16:15, HIGH-DENSITY: Expression and Debates in Politics: “Unintended Politics: Partisan Opinion Expression and Incivility in Incidental Political Discussion” by Yibin Fan, U of Washington, Benjamin Mako Hill, U. of Washington, Patricia Moy, U. of Washington.

Sunday

12:00 – 13:15,  Organizational Communication Research Escalator.  “But Have You Tried to Ignore Them?” A Cross-National Comparison of Resilience Against Gendered Cyberhate in India and the USA by Bedadyuti Jha, Purdue U and Jeremy Foote, Purdue U.

15:00 – 16:15, Intergroup Communication Top Papers.  Effects of Racial Minority Language Use on the Conversational Sustenance of Online Discussions by Haomin Lin, University of Washington, and Wang Liao, University of Washington.

Monday

10:30 – 11:45,  NEKO-tiating Later Life: Digital Health, News Habits, and Tech Support: Communication and Technology. “Gig Work in Later Life: Sociodemographic and Digital Determinants of Older Adults’ Participation” by Floor Fiers, U of Amsterdam, Will Marler, Tilburg U, and Eszter Hargittai, U of Zurich.

Also, congratulations to Dr. Kaylea Champion, as her dissertation, “Social and Technical Sources of Risk in Sustaining Digital Infrastructure,” will be given the 2025 Annie Lang Dissertation Award from the International Communication Association Information Systems Division. The award will be given out at the ICA 2025 Information Systems business meeting 16:30 – 17:45 in Granite (Regency 3). Kaylea’s dissertation also received the 2025 Faculty Award for Outstanding Research Ph.D. Dissertation Award from the Department of Communication University of Washington. You can read more about Kaylea and her research on her homepage here.

Congrats to our CDSC folks on their accomplishments, and have safe travels to Denver this weekend!

CDSC member Kaylea Champion’s dissertation, “Social and Technical Sources of Risk in Sustaining Digital Infrastructure,” has been selected for two awards: the 2025 Annie Lang Dissertation Award from the International Communication Association Information Systems Division, and the 2025 Faculty Award for Outstanding Research – Ph.D. Dissertation Award from the Department of Communication University of Washington.

Kaylea’s dissertation develops new methods to measure and understand risks to our shared digital infrastructure–including platforms, communication systems, the web, and the cloud. Digital infrastructure faces a form of risk called underproduction–highly important, but low-quality software. She argues we can identify this risk by examining the social and technical conditions of software production communities.

Using analysis methods she developed and validated, she found thousands of at-risk software packages. These packages are often old, or written in older languages. However, simply directing more resources toward software maintenance may not be enough: at-risk packages are more likely to be maintained by larger numbers of people and by people who are already highly active in the development community. She identified two factors associated with lower risk: empowerment and retention. Kaylea’s work joins a growing base of scholarship across the CDSC focusing attention toward contributors as a key part of building thriving peer production communities for the benefit of the greater public.

Kaylea will join the faculty of the University of Washington Bothell as an Assistant Professor in the Division of Computing and Software Systems, School of STEM, in Fall 2025.

Throughout their lifecycles, the online communities that steward public information goods can face a range of threats to their sustainability. Over the course of its existence, Wikipedia, one of the most visible online knowledge commons, has battled the following challenges:

• Strategic degradation and pollution, through the introduction of misinformation and vandalism affecting its article base;
• Governance capture of some language projects by small groups of ideologically motivated editors;
• Commercial appropriation and disintermediation of its knowledge base by generative AI companies; and
• Escalating legitimacy attacks by partisan actors seeking to undermine the online encyclopedia’s perceived credibility as an information resource.

At our 11th Science of Community Dialogue on April 4th, which featured a conversation with Zarine Kharazian (University of Washington) and Professor Paul Gowder (Northwestern University), we discussed the role of online community governance in responding to these threats. Following up on this discussion, we are excited to share a research brief that both outlines some of the evolving threats that public information goods face as they mature and offers strategies that community leaders can adopt to address them. We hope that this synthesis inspires reflection and discussion on the nature of the public information goods various online communities maintain and the role of community governance institutions in defending the goods at stake and building public trust and legitimacy.

Community decay and abandonment are persistent risks to free/libre and open source software (FLOSS) projects. As such, large institutions such as GitHub or Mozilla offer advice to FLOSS projects on how to organize their work for sustainability and community-building. Guides recommend the production of README files and CONTRIBUTING guides as useful tools in recruiting new project contributors and driving activity. Yet though the development of these documents is widely-suggested, there is little empirical study of how projects use these files and what happens when documents are introduced to projects.

In one of the first empirical studies of the initial publication of documentation files, our findings suggest a disconnect between institutional recommendations and FLOSS projects’ actual use the documents. Instead of being proactively developed and community-oriented, first-version files are published following an increase of activity and focus on the functional details of using or contributing to the library.  Often, documents are published with hardly any content at all, with projects publishing empty or minimal files. We found no support for any causal claims around the nature of a document’s depth or focus and subsequent project activity. 

Our results suggest that projects may use these documents to perform a norm. The publication of empty documentation files implies that an empty file in their home directory was more important to projects than any benefits of document contents. Our results also suggest that projects may use these documents to ‘get their house in order’ after an influx of activity.

The guides and recommendations that we examined did not specify when projects should take what actions to grow sustainably. This lack of specificity limits the utility for projects trying to figure out how to sustain themselves in ever-changing environments. The work necessary to develop meticulous, community-oriented files may not be a good time investment for early-stage projects with only a handful of contributors. More research is necessary to develop useful context-situated recommendations to support FLOSS projects adaptation. 

This paper was presented a few weeks ago in Ottawa at the International Conference on Cooperative and Human Aspects of Software Engineering (CHASE) 2025. A pre-print of the paper can be found here; the data and code for the project can be found here.

This research wouldn’t be possible without the work of the volunteers producing FLOSS who have made their work available for inspection. We also gratefully acknowledge support from the Ford/Sloan Digital Infrastructure Initiative (Sloan Award 2018-113560) and the National Science Foundation (Grant IIS-2045055). This work was conducted using the Hyak supercomputer at the University of Washington as well as research computing resources at Northwestern University.

Does your work touch open source, communities, technology, or cooperation? Do you want to help bridge the gaps between research and practice? Join us at FOSSY! The Free and Open Source Software Yearly conference (FOSSY) is back this summer and the call for proposals is open!

“I always enjoy the blend of researcher and contributor perspectives in the Science of Community track. The presentations are always great, surpassed only by the follow up conversations in the hall afterwards!” – Matt Gaughan, CDSC member and PhD student

We’ll be running the Science of Community track, and are looking for presenters to speak to an audience of FOSS practitioners, developers, community organizers, contributors, and people just generally into and curious about FOSS. 

The Science of Community track is inspired by the CDSC Science of Community Dialogues, which bring together practitioners and researchers to discuss scholarly work that is relevant to the efforts of practitioners. As researchers, we benefit so much from the communities we work with and study and we want them to also learn from the research they so generously take part in. While the Dialogues cover a broad range of topics and communities, FOSSY presentations will focus on how that work relates to free and open source software communities, projects, and practitioners.

FOSSY is a low-stress opportunity to talk to people who your work can benefit. For topics, consider presenting implications from past papers, synthesizing work from your field overall, or floating ideas and problems (lightning talks! long talks! short talks!). A full track description and answers to common questions is available on our wiki.

The CFP deadline is April 28th and uses this form.

We held our 11th Science of Community Dialogue on April 4th, with Zarine Kharazian (University of Washington) and Professor Paul Gowder (Northwestern University) sharing their research on misinformation and propaganda in online communities, limitations of approaches that neglect community governance, and insights on democratizing platforms and society.

Zarine kicked off the conversation by highlighting recent events regarding allegations and attacks on Wikipedia, and how these legitimacy attacks affect communities engagement with encyclopedic knowledge and collective sense-making infrastructures. She explored organizational and institutional approaches that could enable communities to effectively steward information commons in the face of these attacks.

In his book The Networked Leviathan, Paul advocated for more participatory and multi-level governance as a corrective to the “democratic deficit” and lack of accountability of social media platforms. In this dialogue, he discussed threats and updates to this framework in light of recent developments.

Thank you to everyone who joined us and participated in this insightful and timely conversation. We greatly appreciate Zarine and Paul taking the time to share their views and research on community governance.

We all wear a lot of hats as researchers. Cowboy hats as we lasso and wrangle data. Noir-style fedoras when we are pinning post-it’s to a wall and stringing together our evidence. Berets when we ponder over the perfect artistic metaphor to describe our results. Sitting dusty in the corner is the tocque, the baker’s cap. We don the tocque, the billowing white like a cloth mushroom, when we’re kneading our ideas and getting ready to bake them. Too often, we don’t really linger in that role, our ideas need to move forward: there are deadlines to meet and papers to publish! However, once a year, the CDSC invites its members to become bakers and play around with our half-baked ideas together in the Great Half Bake-Off.

One of the hallmark’s of the CDSC’s annual retreat, in which our distributed collective gathers at one of the member universities to be merry (and work) together in meat space for a few days, is the annual Great Half Bake-Off (GHBO). The Great Half Bake-Off is an opportunity for members of the group to present an idea in a rapid-fire way that they’re interested in. They might not know where to start with the idea, or the idea seems too big or out there to seem feasible.

The half-bake off, being a part of our retreat at the beginning of the academic year does a lot to glue the group together. With an intention of sharing an idea that we actually care about, but might in other instances be too afraid to share because it feels too undercooked, we become comfortable sharing our ideas with each other, no matter what the stage of thought we’ve put into the project idea.

The exercise helps us learn about each other as it reveals the gulf between what we all work on and what some of the projects we only dream about are. It helps us become more comfortable with airing out our inspirations and ideals. It overall encourages a moment of playfulness and camaraderie.

How Do We Bake (Or, How You Can Host Your Own Great Half Bake-Off)

The logistics for the GHBO are relatively simple. Notify your bakers at least a few weeks before your event to think about what half-baked ideas they want to bring to the table. Provide a collaborative slide deck for them to include a slide if they’d like to organize their half-baked thoughts in that way. We give our bakers 2-3 minutes (but no more!) to present their ideas, and a minute or two to field questions. Then, at the end, for the grand prize of a Silly Little Trophy, we all vote for who had the most half-baked idea. This is a key element to the process: voting on the merits not of the idea’s potential success or creativity, but the vague, unreliable measure of “half-bakedness.”

This is the slide template we give in advance, should people want to use it! Sometimes it’s nice to bake with a recipe. :’)

Some Half-Baked Categories to Prepare Your Bakers:

• Long Shots – Maybe there’s a project within your repertoire, but you’re not sure how you would find the time, money, or energy to see it through. Sound’s half-baked!
• Mysteries – Have a research question that you’re just not sure where even to begin to answer? Perfect!
• New Flavors – Perhaps you have a project that you’re thinking about but it uses a method that you’ve never used (or even seen someone else use!)
• Something Silly – We all have burning questions that might … not add a lot to the public good if we were to answer them. Now’s your chance to talk about those!
• Literally anything else – by now, hopefully you get the idea. As long as it is mushy and half-baked – with enough room for your colleagues to poke at its spongy undoneness, it’s worthy of being called half-baked.

  Winner of GHBO 2024, Emily Zou’s, half-baked idea!

What Comes Out of the Half-Baked Off

As we’ve discussed, the main benefits of the Great Half Bake-Off come not necessarily from the immaculate pastries that we pull out of the oven at the end of the ordeal, the goodness of the half bake off exists in the way we get to have a good time with each other, and see deeper into how we each begin to craft our doughs. In fact, more often than not, our ideas from the event many moons later remain just as half-baked as when we presented them. Sohyeon, the 2022 GHBO champion, in a 2024 update on the status of her winning project proposal gleefully remarked that “the idea remains half-baked.”

As I’m sure many before me can relate to… after a class here, a conversation with someone there, and a hop, skip, and a jump later, somehow I tumbled my way into grad school!

When I began graduate school, I knew I was interested in the intersection of health communication and online communities, but beyond that, I wasn’t entirely sure what direction I wanted to go in! Fortunately, UW is home to two labs dedicated to these areas and I have been rotating between them throughout my first year in the Communication department.

Last quarter, I started my rotation with the CDSC and began developing my first research project (!!) focused on health-related stigma trends on Reddit. I’ve always been interested in how online communities offer supplementary support for individuals dealing with health-related issues, and I knew I wanted to do something that explored how stigma impacts health-related discussion trends. Various research has been done on stigma communication in online communities. For example, Brown and colleagues (2023) investigated types of stigma tweets associated with different types of health-related stigma on X (formerly known as Twitter) and found that although stigma was prevalent for each condition they studied, anti-stigma messages were more common than the various types of stigma communication. I want to expand on this research area by diving deeper into the motivations and reasoning participants have for joining and contributing to health-related communities online!

This quarter, while I have continued working on my health-related stigma project I also have rotated into the Health Equity Action Lab (HEAL). Given my interest in online communities, I was brought onto a project examining correlates of online support in women experiencing postpartum depression. 

I have since taken the lead on a subset of the data related to Internet use as a form of support. Within the HEAL study, 83% of women who sought information or support online met the criteria for postpartum depression. Research done by Stellefson and colleagues (2018) suggest that greater use of the Internet may be a result of knowledge gaps created by poor patient-provider communication. Our goal is to identify the factors that increase the likelihood of women within this population to seek out support!

Currently, I am categorizing and coding open-ended survey responses to determine whether eHealth literacy is linked to specific apps or websites as resources for information or support among women experiencing postpartum depression. So far, I have found survey participants often turn to WebMD, Reddit, and Facebook as sources of information and support.

Both my project examining health-related stigma on Reddit and my project identifying online destinations for support-seekers demonstrate how the Internet and online communities offer valuable resources for those seeking help, and foster connections with others who share similar experiences. Have you ever turned to an online community to seek out support?

Join the Community Data Science Collective (CDSC) for our 11th Science of Community Dialogue! This Community Dialogue will take place on April 4th at 12:00 pm CT. This Dialogue focuses on resisting online information manipulation and the role of community governance. Professor Paul Gowder (Northwestern University) will join Zarine Kharazian (University of Washington) to present recent research on topics including:

• Exploring threats like misinformation and propaganda in online communities.
• Limitations of approaches that neglect community governance.
• Tradeoffs in governance models, such as those of Facebook, Bluesky, and Wikipedia.
• Strategies to protect information commons.
• Participatory governance for platforms.
• Insights on democratizing platforms and society.

A full session descriptions is on our website. Register online.

What is a Dialogue?

The Science of Community Dialogue Series is a series of conversations between researchers, experts, community organizers, and other people who are interested in how communities work, collaborate, and succeed. You can watch this short introduction video with Aaron Shaw.

What is the CDSC?

The Community Data Science Collective (CDSC) is an interdisciplinary research group made of up of faculty and students at the University of Washington Department of Communication, the Northwestern University Department of Communication Studies, the Carleton College Computer Science Department, the School of Information at UT Austin, and the Purdue University School of Communication.

Learn more

If you’d like to learn more or get future updates about the Science of Community Dialogues, please join the low volume announcement list.