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Christopher Boyer

@cboyer.bsky.social

Assistant Professor, Case Western Reserve University (CCLCM). Staff Biostatistician, Cleveland Clinic. Epidemiologist interested in causal inference, infectious disease, trial design https://christopherbboyer.com/about.html #causalsky #statssky #episky

197 Followers  |  377 Following  |  78 Posts  |  Joined: 27.09.2023  |  2.238

Latest posts by cboyer.bsky.social on Bluesky

What I want: a handful of rigorous, randomized evaluations of AI use in science with clear protocols of use, careful measurement, and real endpoints.

What I am getting: a million sloppy studies either using AI to crawl massive publication databases or little trials reporting nonserious benchmarks.

17.01.2026 14:50 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

Would suggest Eric TTs papers on universal difference-in-differences and generalized difference-in-differences as they are essential equi-confounding and calibration correction approaches but generalize beyond just additive scale and allow for different outcome types.

16.01.2026 17:36 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0
Preview
GitHub - etverse/negatr: R package for negative control analysis. R package for negative control analysis. Contribute to etverse/negatr development by creating an account on GitHub.

Very interesting! I became quite obsessed with negative controls/test lately ๐Ÿ˜…
Iโ€™m trying to put several methods in here: github.com/etverse/negatr

16.01.2026 17:02 โ€” ๐Ÿ‘ 1    ๐Ÿ” 1    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

Oh nice! For the difference-in-differences approach are you assuming additive scale aqui-confounding?

16.01.2026 17:14 โ€” ๐Ÿ‘ 0    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

For longer discussion of the underlying identification assumptions and their plausibility in any real-world scenarios see our recent Epidemiology paper:

journals.lww.com/10.1097/EDE....

16.01.2026 16:30 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0
Can test-negative results correct hidden confounding? โ€“ Christopher B. Boyer A simulation walk-through of negative control outcomes for vaccine effectiveness

New blog post:

christopherbboyer.com/posts/2025-1...

A simple simulation to show when/how test-negative results can be used to correct unmeasured confounding.

16.01.2026 16:30 โ€” ๐Ÿ‘ 2    ๐Ÿ” 1    ๐Ÿ’ฌ 2    ๐Ÿ“Œ 0

Maybe theyโ€™ll reconsider after theyโ€™ve had time to put their phone down and d-connect.

14.01.2026 18:00 โ€” ๐Ÿ‘ 0    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

Hmmm blocked by DAGโ€ฆ you must have really confounded them ๐Ÿ™ƒ

14.01.2026 17:19 โ€” ๐Ÿ‘ 4    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

I would also say that original vanilla IV and DID and RDD were much easier to implement (I guess if you do two stage linear models version of PCI itโ€™s about as easy as IV but Iโ€™m not sure this was widely dissseminated)

01.01.2026 17:48 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

In one sense youโ€™re right, but donโ€™t IV and DID themselves fit neatly within PCI framework as special cases (ie DID as a form of negative outcome control with additional parametric restrictions and IV as unconfounded negative exposure control)?

01.01.2026 17:42 โ€” ๐Ÿ‘ 3    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

Better than in another grant application.

31.12.2025 16:22 โ€” ๐Ÿ‘ 2    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

And of course weโ€™re happy that, in the end, we ended up with a healthy happy baby; and privileged that we could swing it financially. But itโ€™s a system that needs fundamental reform.

30.12.2025 17:09 โ€” ๐Ÿ‘ 0    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

Also this was in Massachusetts where at least there was mandated insurance coverage for IVF. And yet still we paid 000s out of pocket.

30.12.2025 17:05 โ€” ๐Ÿ‘ 0    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

Glad this is receiving more scrutiny. Our own fertility journey included not only encounters with private equity owned clinics but also black market deals for drugs due to manufactured shortages. Shares many of the predatory tactics of other industries that prey on vulnerable people.

30.12.2025 17:02 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0
screenshot of my post

screenshot of my post

Big new blogpost!

My guide to data visualization, which includes a very long table of contents, tons of charts, and more.

--> Why data visualization matters and how to make charts more effective, clear, transparent, and sometimes, beautiful.
www.scientificdiscovery.dev/p/salonis-gu...

09.12.2025 20:28 โ€” ๐Ÿ‘ 800    ๐Ÿ” 318    ๐Ÿ’ฌ 22    ๐Ÿ“Œ 50

Today I had to docu-sign some legal agreements for grants and noticed they now offer an AI summary that they warn โ€œmay be inaccurateโ€โ€ฆ Truly what are we doing here fam?

10.12.2025 13:06 โ€” ๐Ÿ‘ 3    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

Now we have sludge units

10.12.2025 13:00 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

2. The relevant identification assumption here also isnโ€™t exchangeability anyway itโ€™s parallel trends which is both slightly weaker (in that it allows some forms of unmeasured confounding) and stronger (in that it imposes parametric restrictions on possible DGPs)

10.12.2025 12:02 โ€” ๐Ÿ‘ 2    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

Two points: 1. I guess what Iโ€™m saying is that itโ€™s not that conditioning on the group is causing bias but that the confounding structure could be different for the subgroup. Eg draw me the DAG/SWIG where conditioning on birth, which is also the treatment variable of interest, is an issue.

10.12.2025 12:02 โ€” ๐Ÿ‘ 0    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0
Preview
Long-term effects of pregnancy and childbirth on sleep satisfaction and duration of first-time and experienced mothers and fathers AbstractStudy Objectives. To examine the changes in mothersโ€™ and fathersโ€™ sleep satisfaction and sleep duration across prepregnancy, pregnancy, and the pos

I maintain that this is an excellent benchmark for d-type effect sizes:

Sleep satisfaction & duration declined with childbirth & reached a nadir during the first 3 months postpartum, with women more strongly affected (satisfaction d = -0.79, duration minus 62 min, d = -0.90)>

09.12.2025 09:50 โ€” ๐Ÿ‘ 82    ๐Ÿ” 25    ๐Ÿ’ฌ 6    ๐Ÿ“Œ 2

Yes! And to be clear, as a father to a 3- and 1-year old, I still think this is among the cleanest causal effects one could imagine haha.

09.12.2025 16:40 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

E.g. doing post exposure prophylaxis when my mean time to prophylaxis is 3 days may be very different than when mean time is 7 days, even if both are well defined and identified.

09.12.2025 16:27 โ€” ๐Ÿ‘ 0    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

They may be systematically different, but I could still run a well-defined trial of post-exposure intervention by enrolling them and randomizing among subgroup who survives. My effect would just entirely depend on distribution of who survives and would be highly โ€œparticularisticโ€.

09.12.2025 16:24 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

E.g. Iโ€™m interested in effects of post-exposure interventions in infectious disease. For short incubation period infections, every day that I delay post exposure defines a different subgroup of people surviving without outcome.

09.12.2025 16:24 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

But donโ€™t those biases relate to my ability to generalize rather than identifiability of effect within subgroup? Only ask because this comes up all the time when thereโ€™s a severe selecting event prior to treatment.

09.12.2025 16:24 โ€” ๐Ÿ‘ 1    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

I.e., what would it mean, interventionally, for couples where a birth occurred to speak of their sleep if it had not occurred?

09.12.2025 14:48 โ€” ๐Ÿ‘ 2    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

Sure it may not generalize to populations with other distributions of loss/infertility but the subgroup is well-defined. The only ambiguous part is what their untreated potential outcome is?

09.12.2025 14:48 โ€” ๐Ÿ‘ 2    ๐Ÿ” 0    ๐Ÿ’ฌ 1    ๐Ÿ“Œ 0

Donโ€™t most of those concerns relate to early exposures (eg around conception or early pregnancy). Here the main exposure is โ€œbirthโ€ and the nature of fixed effects is to target effect among the treated, ie couples where a live birth occurs.

09.12.2025 14:48 โ€” ๐Ÿ‘ 2    ๐Ÿ” 0    ๐Ÿ’ฌ 2    ๐Ÿ“Œ 0

Now published!

journals.lww.com/epidem/abstr...

02.12.2025 18:15 โ€” ๐Ÿ‘ 4    ๐Ÿ” 0    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

If you've ever found any of my work helpful, consider donating to the Python Software Foundation

Learning Python during my PhD and translating everything between programming languages helped me build my understanding of causal inference. It is also why I know estimating equations as well as I do

28.10.2025 12:18 โ€” ๐Ÿ‘ 10    ๐Ÿ” 3    ๐Ÿ’ฌ 0    ๐Ÿ“Œ 0

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