Arman Oganisian
banner
stablemarkets.bsky.social
Arman Oganisian
@stablemarkets.bsky.social
Statistician | Assistant professor @ Brown University Dept of Biostatistics | Developing nonparametric Bayesian methods for causal inference.

Research site: stablemarkets.netlify.app

#statsky
Why I find Bayesian nonparametric causal inference compelling in one figure.

The key distinction is btwn (1) "known" vs (2) "unknown" quantities: Make inferences about (2) conditional on (1).

Want cond. avg trt effects? Condition on data, make inferences about regression lines
September 24, 2025 at 3:41 PM
... and how identifiability conditions may be read off a Single World Intervention Graph (SWIG) template for the implicit DTR.
September 2, 2025 at 2:50 PM
We discuss formalize connections between g-methods that use discrete-time versus continuous-time models adjustment models and the relative pros/cons of each...
September 2, 2025 at 2:50 PM
In causal inference problems w/ sequential treatments, long stretches of time may elapse between treatment decisions

This paper, in press at Epidemiology, was really fun to write: it discusses biases that may arise & corresponding adjustment via g-methods
arxiv.org/abs/2508.21804
September 2, 2025 at 2:50 PM
ChatGPT explains double robustness to gen z crowd.
August 25, 2025 at 12:54 PM
I originally wrote to share with trainees but was encouraged to post it online. I address a lot of subtleties:

Why does sample-level inference need stronger assumptions? When should/n’t we impute counterfactuals? How does this differ from g-computation? Do we really need to Bayesian bootstrap?
August 22, 2025 at 12:35 PM
New paper on Bayesian Diff-in-Diff methods:

www.arxiv.org/abs/2508.02970

When doing DiD, many inspect the difference in trends in the pre-period to “check” whether parallel trends (PT) holds.

But PT is fundamentally uncheckable since it must hold in the post-period as well.

What’s going on?
August 10, 2025 at 6:10 PM
Today’s mcmc chains are invoking feelings of dread, woe, and malice.

(credit to chatgpt) #statsky
April 3, 2025 at 2:11 PM
Bayesian Causal Inference w/ survival outcomes has never been so easy!

Check out work by Biostats PhD student Han Ji now accepted at Observational Studies.

Convenient syntax, help files, custom S3 classes, & efficient MCMC via Stan in back-end

arxiv.org/pdf/2310.12358

github.com/RuBBiT-hj/ca...
March 10, 2025 at 2:55 PM
So many of the responses go down a Bayesian road - it’s inevitable if all models are indeed equally plausible. Reminds me of one of my favorite quotes from Radford Neal
March 9, 2025 at 7:42 PM
Software update: Daniel Kowal (Cornell) was kind enough to include an implementation of our hierarchical Bayesian bootstrap in his SeBR R package (which also has other great regression tools!) - complete w/ help files and examples.

t.co/ekVZXcDqJy
t.co/LuTO9VSJfs
March 7, 2025 at 4:46 PM
Finished drafting lecture notes on two of my favorite results in Bayesian inference:

1) The empirical Bayes derivation of the James-Stein Estimator

2) the (first order) equivalence of Bayesian bootstrap covariance, Efron’s bootstrap covariance, and the robust sandwich covariance estimators
February 9, 2025 at 5:03 PM
Check out this new paper by Biostatistics PhD Candidate Esteban Fernández-Morales. He develops innovative Bayesian spatial shrinkage methods for causal inference with spillovers and uses it to assess the effect of Philadelphia's 2017 beverage tax.

arxiv.org/abs/2501.08231
January 21, 2025 at 5:12 PM