Causal Analysis in Theory and Practice

March 1, 2018

Special Greeting from the UCLA Causality Blog

Filed under: Announcement — Judea Pearl @ 10:34 pm

Dear friends in causality research,

This greeting is somewhat different from those you have been receiving in the past 18 years (Yes, it has been that long, see, January 1, 2000). Instead of new results, passionate discussions, breakthroughs, controversies, and question and answers sessions, this greeting brings you a musical offering: The Book of Why. It is a new book that I have co-authored recently with Dana MacKenzie (, forthcoming May 15, 2018. The book tells the story, in layman’s terms, of the new science of cause and effect, the one we have been nourishing, playing with, and marveling at on this blog.

By “the new science” I mean going back, not merely to the causal revolution of the past few decades, but all the way to the day when scientists first assigned a mathematical symbol to a causal relation.

Joining me in this journey you will see how leaders in your own field managed to cope with the painful transition from statistical to causal thinking.

Despite my personal obsession with mathematical tools, this book has taught me that the story of causal inference looks totally different from the conceptual, non-technical viewpoint of our intended readers. So different in fact that I occasionally catch myself tuning to the music of The Book of Why when seeking a deeper understanding of a dry equation. I hope you and your students find it as useful and as enjoyable.

The publisher’s description can be viewed here: while the Table of Content and sample chapters can be viewed here:

Our publisher also assures us that the book can be pre-ordered at no extra cost, and on your favorite website.

And may our story be inscribed in the book of worthy causes.


January 10, 2018

2018 Winter Update

Filed under: Announcement,General — Judea Pearl @ 10:07 pm

Dear friends in causality research,

Welcome to the 2018 Winter Greeting from the UCLA Causality Blog. This greeting discusses the following topics:

1.  A report is posted, on the “What If” workshop at the NIPS conference  (see December 19, 2017 post below). It discusses my presentation of: Theoretical Impediments to Machine Learning, a newly revised version of which can be viewed here. []

2. New posting: “Facts and Fiction from the Missing Data Framework”. We are inviting discussion of two familiar mantras:
Mantra-1. “The role of missing data analysis in causal inference is well understood (eg causal inference theory based on counterfactuals relies on the missing data framework).
Mantra-2. “while missing data methods can form tools for causal inference, the converse cannot be true.”

We explain why we believe both mantras to be false, but we would like to hear you opinion before firming up our minds.

3. A review paper is available here:
Titled: “Graphical Models for Processing Missing Data.” It explains and demonstrates why missing data is a causal inference problem.

4. A new page is now up, providing information on “The Book of Why”
It contains Table of Contents and excerpts from the book.

5. Nominations are now open for the ASA Causality in Education Award. The nomination deadline is March 1, 2018. For more information, please see

6. For those of us who were waiting patiently for the Korean translation of Primer — our long wait is finally over. The book is available now in colorful cover and in optimistic North Korean accent.

Don’t miss the gentlest introduction to causal inference.

Enjoy, and have a productive 2018.

May 1, 2017

UAI 2017 Causality Workshop

Filed under: Announcement — Judea Pearl @ 8:35 pm

Dear friends in causality research,

We would like to promote an upcoming causality workshop at UAI 2017. See the details below for more information:

Causality in Learning, Inference, and Decision-making: Causality shapes how we view, understand, and react to the world around us. It’s a key ingredient in building AI systems that are autonomous and can act efficiently in complex and uncertain environments. It’s also important to the process of scientific discovery since it underpins how explanations are constructed and the scientific method.

Not surprisingly, the tasks of learning and reasoning with causal-effect relationships have attracted great interest in the artificial intelligence and machine learning communities. This effort has led to a very general theoretical and algorithmic understanding of what causality means and under what conditions it can be inferred. These results have started to percolate through more applied fields that generate the bulk of the data currently available, ranging from genetics to medicine, from psychology to economics.

This one-day workshop will explore causal inference in a broad sense through a set of invited talks,  open problems sessions, presentations, and a poster session. In this workshop, we will focus on the foundational side of causality on the one hand, and challenges presented by practical applications on the other. By and large, we welcome contributions from all areas relating to the study of causality.

We encourage co-submission of (full) papers that have been submitted to the main UAI 2017 conference. This workshop is a sequel to a successful predecessor at UAI 2016.

Dates/Locations: August 15, 2017; Sydney, Australia.

Speakers: TBA

Registration and additional information:

April 14, 2017

West Coast Experiments Conference, UCLA 2017

Filed under: Announcement — Judea Pearl @ 9:05 pm

Hello friends in causality research!

UCLA is proud to host the 2017 West Coast Experiments Conference. See the details below for more information:

West Coast Experiments Conference: The WCE is an annual conference that brings together leading scholars and graduate students in economics, political science and other social sciences who share an interest in causal identification broadly speaking. Now in its tenth year, the WCE is a venue for methodological instruction and debate over design-based and observational methods for causal inference, both theory and applications.

Speakers: Judea Pearl, Rosa Matzkin, Niall Cardin, Angus Deaton, Chris Auld, Jeff Wooldridge, Ed Leamer, Karim Chalak, Rodrigo Pinto, Clark Glymour, Elias Barenboim, Adam Glynn, and Karthika Mohan.

Dates/Location: The tenth annual West Coast Experiments Conference will be held at UCLA on Monday, April 24 and Tuesday, April 25, 2017, preceded by in-depth methods training workshops on Sunday, April 23. Events will be held in the Covel Commons Grand Horizon Ballroom, 200 De Neve Drive, Los Angeles, CA 90095.

Fees: Attendance is free!

Registration and details: Space is limited; for a detailed schedule of events and registration, please visit:

April 13, 2017

Causal Inference with Directed Graphs – Seminar

Filed under: Announcement — Judea Pearl @ 5:27 am


We would like to promote another causal inference short course. This 2-day seminar won the 2013 Causality in Statistics Education Award, given by the American Statistical Association. See the details below for more information:

Causal Inference with Directed Graphs: This seminar offers an applied introduction to directed acyclic graphs (DAGs) for causal inference. DAGs are a powerful new tool for understanding and resolving causal problems in empirical research. DAGs are useful for social and biomedical researchers, business and policy analysts who want to draw causal inferences from non-experimental data. The chief advantage of DAGs is that they are “algebra-free,” relying instead on intuitive yet rigorous graphical rules.

Instructor: Felix Elwert, Ph.D.

Who should attend: If you want to understand under what circumstances you can draw causal inferences from non-experimental data, this course is for you. Participants should have a good working knowledge of multiple regression and basic concepts of probability. Some prior exposure to causal inference (counterfactuals, propensity scores, instrumental variables analysis) will be helpful but is not essential.

Tuition: The fee of $995.00 includes all seminar materials.

Date/Location: The seminar meets Friday, April 28 and Saturday, April 29 at Temple University Center City, 1515 Market Street, Philadelphia, PA 19103.

Details and registration:

April 8, 2017

Causal Inference Short Course at Harvard

Filed under: Announcement — Judea Pearl @ 2:31 am


We’ve received news that Harvard is offering a short course on causal inference that may be of interest to readers of this blog. See the details below for more information:

An Introduction to Causal Inference: This 5-day course introduces concepts and methods for causal inference from observational data. Upon completion of the course, participants will be prepared to further explore the causal inference literature. Topics covered include the g-formula, inverse probability weighting of marginal structural models, g-estimation of structural nested models, causal mediation analysis, and methods to handle unmeasured confounding. The last day will end with a “capstone” open Q&A session.

Instructors: Miguel Hernán, Judith Lok, James Robins, Eric Tchetgen Tchetgen & Tyler VanderWeele

Prerequisites: Participants are expected to be familiar with basic concepts in epidemiology and biostatistics, including linear and logistic regression and survival analysis techniques.

Tuition: $450/person, to be paid at the time of registration. Tuition will be waived for up to 2 students with primary affiliation at an institution in a developing country.

Date/Location: June 12-16, 2017 at the Harvard T.H. Chan School of Public Health

Details and registration:

February 22, 2017

Winter-2017 Greeting from UCLA Causality Blog

Filed under: Announcement,Causal Effect,Economics,Linear Systems — bryantc @ 6:03 pm

Dear friends in causality research,

In this brief greeting I would like to first call attention to an approaching deadline and then discuss a couple of recent articles.

Causality in Education Award – March 1, 2017

We are informed that the deadline for submitting a nomination for the ASA Causality in Statistics Education Award is March 1, 2017. For purpose, criteria and other information please see .

The next issue of the Journal of Causal Inference (JCI) is schedule to appear March, 2017. See

MY contribution to this issue includes a tutorial paper entitled: “A Linear ‘Microscope’ for Interventions and Counterfactuals”. An advance copy can be viewed here:

Overturning Econometrics Education (or, do we need a “causal interpretation”?)

My attention was called to a recent paper by Josh Angrist and Jorn-Steffen Pischke titled: “Undergraduate econometrics instruction” (A NBER working paper)

This paper advocates a pedagogical paradigm shift that has methodological ramifications beyond econometrics instruction; As I understand it, the shift stands contrary to the traditional teachings of causal inference, as defined by Sewall Wright (1920), Haavelmo (1943), Marschak (1950), Wold (1960), and other founding fathers of econometrics methodology.

In a nut shell, Angrist and Pischke  start with a set of favorite statistical routines such as IV, regression, differences-in-differences among others, and then search for “a set of control variables needed to insure that the regression-estimated effect of the variable of interest has a causal interpretation”. Traditional causal inference (including economics) teaches us that asking whether the output of a statistical routine “has a causal interpretation” is the wrong question to ask, for it misses the direction of the analysis. Instead, one should start with the target causal parameter itself, and asks whether it is ESTIMABLE (and if so how), be it by IV, regression, differences-in-differences, or perhaps by some new routine that is yet to be discovered and ordained by name. Clearly, no “causal interpretation” is needed for parameters that are intrinsically causal; for example, “causal effect”, “path coefficient”, “direct effect”, “effect of treatment on the treated”, or “probability of causation”.

In practical terms, the difference between the two paradigms is that estimability requires a substantive model while interpretability appears to be model-free. A model exposes its assumptions explicitly, while statistical routines give the deceptive impression that they run assumptions-free (hence their popular appeal). The former lends itself to judgmental and statistical tests, the latter escapes such scrutiny.

In conclusion, if an educator needs to choose between the “interpretability” and “estimability” paradigms, I would go for the latter. If traditional econometrics education
is tailored to support the estimability track, I do not believe a paradigm shift is warranted towards an “interpretation seeking” paradigm as the one proposed by Angrist and Pischke,

I would gladly open this blog for additional discussion on this topic.

I tried to post a comment on NBER (National Bureau of Economic Research), but was rejected for not being an approved “NBER family member”. If any of our readers is a “”NBER family member” feel free to post the above. Note: “NBER working papers are circulated for discussion and comment purposes.” (page 1).

September 11, 2016

An interesting math and causality-minded club

Filed under: Announcement — bryantc @ 6:08 pm

from Adam Kelleher:

The math and algorithm reading group ( is based in NYC, and was founded when I moved here three years ago. It’s a very casual group that grew out of a reading group I was in during graduate school. Some friends who were math graduate students were interested in learning more about general relativity, and I (a physicist) was interested in learning more math. Together, we read about differential geometry, with the goal of bringing our knowledge together. We reasoned that we could learn more as a group, by pooling our different perspectives and experience, than we could individually. That’s the core motivation of our reading group: not only are we there to help resolve each other get through the material if anyone gets stuck, but we’re also there to add what else we know (in the format of a group discussion) to the content of the material.

We’re currently reading Causality cover to cover. We’ve paused to implement some of the algorithms, and plan on pausing again soon for a review session. We intend to do a “hacking session”, to try our hands at causal inference and analysis on some open data sets.

Inspired by reading Causality, and realizing that the best open implementations of causal inference were packaged in the (old, relatively inaccessible) Tetrad package, I’ve started a modern implementation of some tools for causal inference and analysis in the causality package in Python. It’s on pypi (pip install causality, or check the tutorial on, but it’s still a work in progress. The IC* algorithm is implemented, along with a small suite of conditional independence tests. I’m adding some classic methods for causal inference and causal effects estimation, aimed at making the package more general-purpose. I invite new contributions to help build out the package. Just open an issue, and label it an “enhancement” to kick of the discussion!

Finally, to make all of the work more accessible to people without more advanced math background, I’ve been writing a series of blog posts aimed at introducing anyone with an intermediate background in probability and statistics to the material in Causality! It’s aimed especially at practitioners, like data scientists. The hope is that more people, managers included (the intended audience for the first 3 posts), will understand the issues that come up when you’re not thinking causally. I’d especially recommend the article about understanding bias, but the whole series (still in progress) is indexed here:

June 21, 2016

Spring Greeting from the UCLA Causality Blog

Filed under: Announcement — bryantc @ 3:13 am

Dear friends in causality research,
This Spring Greeting from UCLA Causality blog contains:
A. News items concerning causality research,
B. New postings, new problems and some solutions.

The American Statistical Association (ASA) has announced recipients of the 2016 “Causality in Statistics Education Award”.
Congratulations go to Onyebuchi Arah and Arvid Sjolander who will receive this Award in July, at the 2016 JSM meeting in Chicago.
For details of purpose and selection criteria, see

I will be giving another tutorial at the 2016 JSM meeting, titled “Causal Inference in Statistics: A Gentle Introduction.”
Details and Abstract can be viewed here:

A3. Causal Inference — A Primer
For the many readers who have inquired, the print version of our new book “Causal Inference in Statistics – A Primer” is now up and running on Amazon and Wiley, and is awaiting your reviews, your questions and suggestions. We have posted a book page for this very purpose, which includes selected excerpts from each chapter, errata and updates, and a sample homework solution manual.

The errata page was updated recently under the diligent eye of Adamo Vincenzo. Thank you Adamo!

The Solution Manual will be available for instructors and will incorporate software solutions based on a DAGitty R package, authored by Johannes Textor.  See

Vol. 4 Issue 2 of the Journal of Causal Inference (JCI) is scheduled to appear in September 2018. The current issue can be viewed here: My own contribution to the current issue discusses Savage’s Sure Thing Principle and its ramifications to causal reasoning.

As always, submissions are welcome on all aspects of causal analysis, especially those deemed foundational. Chances of acceptance are inversely proportional to the time it takes a reviewer to figure out what problem the paper attempts to solve. So, please be transparent.

Recollections from the WCE conference at Stanford.

On May 21, Kosuke Imai and I participated in a panel on Mediation, at the annual meeting of the West Coast Experiment Conference, organized by Stanford Graduate School of Business.

Some of my recollections are summarized on our Causality Blog here:

B2. Generalizing Experimental findings
In light of new results concerning generalizability and selection bias, our team has updated the “external validity” entry of wikipedia. Previously, the entry was all about threats to validity, with no word on how those threats can be circumvented. You may wish to check this entry for accuracy and possible extensions.

B3. Causality celebrates its 10,000 citations
According to Google Scholar,, my book Causality (Cambridge, 2000, 2009) has crossed the symbolic mark of 10,000 citations. To celebrate this numerological event, I wish to invite all readers of this blog to an open online party with the beer entirely on me. I dont exactly know how to choreograph such a huge party, or how to make sure that each of you gets a fair share of the inspiration (or beer). So, please send creative suggestions for posting on this blog.

On a personal note: I am extremely gratified by this sign of receptiveness, and I thank readers of Causality for their comments, questions, corrections and reservations which have helped bring this book to its current shape (see


June 10, 2016

Post-doc Causality and Machine Learning

Filed under: Announcement — bryantc @ 7:58 am

We received the following announcement from Isabelle Guyon (UPSud/INRIA):

The Machine Learning and Optimization (TAO) group of the Laboratory of Research in Informatics (LRI) is seeking a postdoctoral researcher for working at the interface of machine learning and causal modeling to support scientific discovery and computer assisted decision making using big data. The researcher will work with an interdisciplinary group including Isabelle Guyon (UPSud/INRIA), Cecile Germain UPSud), Balazs Kegl (CNRS), Antoine Marot (RTE), Patrick Panciatici (RTE), Marc Schoenauer (INRIA), Michele Sebag (CNRS), and Olivier Teytaud (INRIA).

Some research directions we want to pursue include: extending the formulation of causal discovery as a pattern recognition problem (developed through the ChaLearn cause-effect pairs challenge) to times series and spatio-temporal data; combining feature learning using deep learning methods with the creation of cause-effect explanatory models; furthering the unification of structural equation models and reinforcement learning approaches; and developing interventional learning algorithms.

As part of the exciting applications we are working on, we will be leveraging a long term collaboration with the company RTE (French Transmission System Operator for electricity). With the current limitations on adding new transportation lines, the opportunity to use demand response, and the advent of renewable energies interfaced through fast power electronics to the grid, there is an urgent need to adapt the historical way to operate the electricity power grid. The candidate will have the opportunity to use a combination of historical data (several years of data for the entire RTE network sampled every 5 minutes) and very accurate simulations (precise at the MW level), to develop causal models capable of identifying strategies to prevent or to mitigate the impact of incidents on the network as well as inferring what would have happened if we had intervened (i.e., counterfactual).Other applications we are working on with partner laboratories include epidemiology studies about diabetes and happiness in the workplace, modeling embryologic development, modeling high energy particle collision, analyzing human behavior in videos, and game playing.

The candidate will also be part of the Paris-Saclay Center of Data Science and will be expected to participate in the mission of the center through its activities, including organizing challenges on machine learning, and help advising PhD students.

We are accepting candidates with background in machine learning, reinforcement learning, causality, statistics, scientific modeling, physics, and other neighboring disciplines. The candidate should have the ability of working on cross-disciplinary problems, have a strong math background, and the experience or strong desire to work on practical problems.

The TAO group ( conducts interdisciplinary research in theory, algorithms, and applications of machine learning and optimization and it has also strong ties with AppStat the physics machine learning group of the Linear Accelerator Laboratory ( Both laboratories are part of the University Paris-Saclay, located in the outskirts of Paris. The position is available for a period of three years, starting in (the earliest) September, 2016. The monthly salary is around 2500 Euros per month. Interested candidates should send a motivation letter, a CV, and the names and addresses of three referees to Isabelle Guyon.

Contact: Isabelle Guyon (
Deadline: June 30, 2016, then every in 2 weeks until the position is filled.

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