Johan Ugander
@jugander.bsky.social
Associate Professor, Yale Statistics & Data Science. Social networks, social and behavioral data, causal inference, mountains. https://jugander.github.io/
New office trinket: I 3D-printed "Lewitt's missing cube". Quite happy with how it turned out. Many thanks to Paul for sending me the stl file! Skip to 49:55 in his video to appreciate why this is fun.
November 4, 2025 at 9:21 PM
New office trinket: I 3D-printed "Lewitt's missing cube". Quite happy with how it turned out. Many thanks to Paul for sending me the stl file! Skip to 49:55 in his video to appreciate why this is fun.
Connecticut is approach peak fall. Shots from Lake Wintergreen this morning. A glorious start to the day.
October 24, 2025 at 3:21 PM
Connecticut is approach peak fall. Shots from Lake Wintergreen this morning. A glorious start to the day.
My award for most honest paper goes to: arxiv.org/abs/1804.02767 An arxiv-only paper describing v3 of YOLO, a vision algo that already had two published papers. With huge adoption already, authors were out of sell mode and just documented it as best they could. Sec 4 takes honesty to 11. 37k cites.
September 8, 2025 at 12:50 PM
My award for most honest paper goes to: arxiv.org/abs/1804.02767 An arxiv-only paper describing v3 of YOLO, a vision algo that already had two published papers. With huge adoption already, authors were out of sell mode and just documented it as best they could. Sec 4 takes honesty to 11. 37k cites.
Google autocomplete's behavior here reminds me of @msalganik.bsky.social's very nice discussion of "algorithmic confounding" in Bit by Bit (2.4.2): www.bitbybitbook.com/en/1st-ed/ob... and @davidlazer.bsky.social et al.'s "Parable of google flu trends" (2014) paper: www.science.org/doi/10.1126/...
September 3, 2025 at 12:13 PM
Google autocomplete's behavior here reminds me of @msalganik.bsky.social's very nice discussion of "algorithmic confounding" in Bit by Bit (2.4.2): www.bitbybitbook.com/en/1st-ed/ob... and @davidlazer.bsky.social et al.'s "Parable of google flu trends" (2014) paper: www.science.org/doi/10.1126/...
Google autocomplete is asking the important questions.
September 3, 2025 at 12:09 PM
Google autocomplete is asking the important questions.
Does anyone know studies of how FB/X/threads/etc downrank (or don't) external links? According to Adam Mosseri in 11/2024, threads then didn't explicitly downrank links, but notes threads prioritizes like/comments, not clicks, and says people simply don't like/comment much on posts with links.
July 30, 2025 at 6:49 PM
Does anyone know studies of how FB/X/threads/etc downrank (or don't) external links? According to Adam Mosseri in 11/2024, threads then didn't explicitly downrank links, but notes threads prioritizes like/comments, not clicks, and says people simply don't like/comment much on posts with links.
The photos from Ukraine of drone fibre optic debris remind me of Italo Calvino's Ersilia:
"In Ersilia, to establish the relationships that sustain the city's life, the inhabitants stretch strings from the corners of the houses, white or black or gray or black-and-white according to whether… 1/
"In Ersilia, to establish the relationships that sustain the city's life, the inhabitants stretch strings from the corners of the houses, white or black or gray or black-and-white according to whether… 1/
July 2, 2025 at 2:53 AM
The photos from Ukraine of drone fibre optic debris remind me of Italo Calvino's Ersilia:
"In Ersilia, to establish the relationships that sustain the city's life, the inhabitants stretch strings from the corners of the houses, white or black or gray or black-and-white according to whether… 1/
"In Ersilia, to establish the relationships that sustain the city's life, the inhabitants stretch strings from the corners of the houses, white or black or gray or black-and-white according to whether… 1/
📣 Update: I've moved to Yale, joining the Department of Statistics & Data Science as an Associate Professor today (July 1)! The last year's sabbatical here has been great for me and my family, and I am excited for great things ahead! Come visit! Trading the wind of freedom for light and truth!
July 1, 2025 at 3:12 PM
📣 Update: I've moved to Yale, joining the Department of Statistics & Data Science as an Associate Professor today (July 1)! The last year's sabbatical here has been great for me and my family, and I am excited for great things ahead! Come visit! Trading the wind of freedom for light and truth!
The annual snapshots also let us see how the average distances evolved over time. We saw how the average distance came down as the graph grew in nodes and edges. This allowed a conversation with work on "densification", e.g. Leskovec et al. 2007: arxiv.org/abs/physics/... 7/
May 23, 2025 at 6:59 PM
The annual snapshots also let us see how the average distances evolved over time. We saw how the average distance came down as the graph grew in nodes and edges. This allowed a conversation with work on "densification", e.g. Leskovec et al. 2007: arxiv.org/abs/physics/... 7/
Here's the "four degrees" result, where you see that the pairwise distance distribution (for the May 2011 FB graph) is really concentrated around 4. Single countries around 3. The avg distance for the FB graph was 4.74. Sweden and Italy both average 3.9. 6/
May 23, 2025 at 6:59 PM
Here's the "four degrees" result, where you see that the pairwise distance distribution (for the May 2011 FB graph) is really concentrated around 4. Single countries around 3. The avg distance for the FB graph was 4.74. Sweden and Italy both average 3.9. 6/
If it is reasonable to assume a noise distribution (or testable), there's a simple rule for when mean vs. median is more efficient estimator (lower asympt var). I don't remember the derivation, but I think it may assume distribution is symmetric. From (tangential): web.stanford.edu/~jugander/pa...
January 23, 2025 at 4:10 PM
If it is reasonable to assume a noise distribution (or testable), there's a simple rule for when mean vs. median is more efficient estimator (lower asympt var). I don't remember the derivation, but I think it may assume distribution is symmetric. From (tangential): web.stanford.edu/~jugander/pa...
Mary Beth was on the original team that developed and deployed Twitter Birdwatch = X Community Notes, and at FB before that. Insightful thread.
See also the Birdwatch paper, submitted to arxiv the night before Elon took over: arxiv.org/abs/2210.15723
See also the Birdwatch paper, submitted to arxiv the night before Elon took over: arxiv.org/abs/2210.15723
January 8, 2025 at 2:14 PM
Mary Beth was on the original team that developed and deployed Twitter Birdwatch = X Community Notes, and at FB before that. Insightful thread.
See also the Birdwatch paper, submitted to arxiv the night before Elon took over: arxiv.org/abs/2210.15723
See also the Birdwatch paper, submitted to arxiv the night before Elon took over: arxiv.org/abs/2210.15723
And so it came to pass.
January 7, 2025 at 6:26 PM
And so it came to pass.
LLMs playing Scattergories as a parable for questions of diversity/monoculture in genAI, from Manish Raghavan arxiv.org/abs/2412.08610 When there is competition (n>1), you want an LLM with high temperature. But not too high.
December 12, 2024 at 3:23 PM
LLMs playing Scattergories as a parable for questions of diversity/monoculture in genAI, from Manish Raghavan arxiv.org/abs/2412.08610 When there is competition (n>1), you want an LLM with high temperature. But not too high.
Kandiros, Pipis, Daskalakis, and Harshaw have a really Interesting new arxiv preprint on "conflict graph designs" for interference/spillovers: arxiv.org/abs/2411.10908 For GATE estimation the improvement is very significant and I'm optimistic/excited about how the ideas will impact the literature..!
November 22, 2024 at 1:51 PM
Kandiros, Pipis, Daskalakis, and Harshaw have a really Interesting new arxiv preprint on "conflict graph designs" for interference/spillovers: arxiv.org/abs/2411.10908 For GATE estimation the improvement is very significant and I'm optimistic/excited about how the ideas will impact the literature..!
After many conversations with art practitioners and many hours in the art library stacks, this essay is the result. Things also got delightfully weird when we tried to decide how to randomize author order. I'm pretty sure this is the first paper with an author order determined by tarot! 4/4
November 8, 2024 at 3:35 PM
After many conversations with art practitioners and many hours in the art library stacks, this essay is the result. Things also got delightfully weird when we tried to decide how to randomize author order. I'm pretty sure this is the first paper with an author order determined by tarot! 4/4
I gathered US News "peer assessment" response rates. They appear to be at an all time low. Importantly, what explains the sudden rise in the "National Liberal Arts" category response rate, from 28.6% to 47%? Did US News perhaps cook their stats by sending fewer such questionnaires!? Amazing if so. 🤔
October 16, 2024 at 3:21 PM
I gathered US News "peer assessment" response rates. They appear to be at an all time low. Importantly, what explains the sudden rise in the "National Liberal Arts" category response rate, from 28.6% to 47%? Did US News perhaps cook their stats by sending fewer such questionnaires!? Amazing if so. 🤔
🎉 Congratulations to @marionf.bsky.social @kjhealy.bsky.social for their #1 Amazon rating as a new release in Credit Ratings & Repair. Ordinal society gonna ordinal. 🎉
April 23, 2024 at 4:28 AM
🎉 Congratulations to @marionf.bsky.social @kjhealy.bsky.social for their #1 Amazon rating as a new release in Credit Ratings & Repair. Ordinal society gonna ordinal. 🎉
Alternative headline: “The crisis in public education could 'supercharge' election disinformation, US tells the BBC”
February 15, 2024 at 6:44 PM
Alternative headline: “The crisis in public education could 'supercharge' election disinformation, US tells the BBC”
Recently spotted this massive email footer from the French consulate in SF, seems to be a big campaign.
January 24, 2024 at 5:22 PM
Recently spotted this massive email footer from the French consulate in SF, seems to be a big campaign.
Google scholar leaning in to cumulative advantage. Makes me wonder what their objective function looks like. (For the record, I do follow Daron, but under a second email address that fwds to my main, a practice that dates back to when you could only follow max 100 authors.)
December 22, 2023 at 4:38 PM
Google scholar leaning in to cumulative advantage. Makes me wonder what their objective function looks like. (For the record, I do follow Daron, but under a second email address that fwds to my main, a practice that dates back to when you could only follow max 100 authors.)
I would have expected diversity and degree to be more positively correlated than they seem, given how local clustering coeff tends to vary with degree in online social networks (plot below from the 2011 anatomy of FB paper).
October 12, 2023 at 5:22 AM
I would have expected diversity and degree to be more positively correlated than they seem, given how local clustering coeff tends to vary with degree in online social networks (plot below from the 2011 anatomy of FB paper).
Preparing a lecturing for tomorrow, I noticed that the "LinkedIn weak ties" study (Rajkumar et al., 2022) has a very interesting map of the US showing average degree and "average diversity" = 1-(local clustering coeff) = frac of friends who aren't friends. www.science.org/doi/10.1126/...
October 12, 2023 at 5:19 AM
Preparing a lecturing for tomorrow, I noticed that the "LinkedIn weak ties" study (Rajkumar et al., 2022) has a very interesting map of the US showing average degree and "average diversity" = 1-(local clustering coeff) = frac of friends who aren't friends. www.science.org/doi/10.1126/...
October 6, 2023 at 10:17 PM
This weekend I was reading Rick Ridgeway's autobiography, including this bit about his 1983 expedition to the Vinson Massif. This musing about Lincoln Ellsworth's 1935 flights struck me. It's not clear to me when geographers confidently knew that no peaks in Antarctica were taller than Everest…!
October 3, 2023 at 5:51 AM
This weekend I was reading Rick Ridgeway's autobiography, including this bit about his 1983 expedition to the Vinson Massif. This musing about Lincoln Ellsworth's 1935 flights struck me. It's not clear to me when geographers confidently knew that no peaks in Antarctica were taller than Everest…!