Prob/Stats The Causal Revolution and Why You Should Study It

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Judea Pearl revolutionized the understanding of causality in the mid-1990s, earning the Turing Prize for his contributions. His work allows for better questioning in research, enabling the analysis of causal relationships rather than mere correlations. To learn about causality, foundational knowledge in probability and statistics is essential, with three key books recommended for study: "The Book of Why," "Causal Inference in Statistics: A Primer," and "Causality: Models, Reasoning, and Inference." Contrary to traditional statistics, establishing causality can be achieved through observational studies with the right data, and the new causality framework clarifies when to control for confounding variables. Understanding these concepts is crucial for advancing research methodologies and improving analytical outcomes.
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In the mid-1990's, an electrical engineer/computer scientist by the name of Judea Pearl started to change the world by greatly improving our understanding of causality. He brought together many strands of thought that had gone before him, then synthesized them into an integrated whole, with many original contributions as well. For this he was awarded the Turing prize, which is the equivalent of the Nobel prize in computer science.

Here's why you should study causality: because once you've done so, you can begin to ask and answer better questions. For example, instead of merely noting that a hospital's appointments are down at the same time some virus is spreading around, you can ask the better question: is the virus causing appointment counts to go down? The new causality tools give you what you need to answer that question! It is still an inductive procedure, so it's not as though you go from induction to deduction. However, you're asking and answering the questions people really want to know: the "why" questions.

Here's how to learn the new causality. Prerequisites: probability and statistics, the more the better. If you've had a typical calculus-based version, you'd certainly be well-prepared. However, the first book on the list only requires basic probability and statistics. If you want to be able to do all the computations yourself, you would need more background to get through Books 2 and especially 3.

Study these three books, in this order.

  1. The Book of Why, by Judea Pearl and Dana Mackenzie.
  2. Causal Inference in Statistics: A Primer, by Judea Pearl, Madelyn Glymour, and Nicholas P. Jewell.
  3. Causality: Models, Reasoning, and Inference, by Judea Pearl.

Teaser: contrary to the standard doctrine of traditional statistics, which I had learned, you do not always need to have a randomized controlled trial (RCT) in order to establish causality! With the right data, even an observational study can give you causality (this is how we know that smoking causes lung cancer, e.g., when the right RCT would be unethical).

Another teaser: Have you ever wondered how you can tell when to control for a possibly confounding variable or not? The new causality not only makes the whole concept of confounding much clearer, but tells you when you need to condition on a variable, and when NOT to condition on a variable! (Hint: sometimes conditioning on a variable gives you the WRONG answer!)

Highly recommended!
 
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scottdave said:
And on a lighter note, check out these Spurious Correlations - https://tylervigen.com/spurious-correlations
Right! Although, as the books above point out, the correct statement is not "Correlation does not imply causation." A better statement is, "Correlation often implies causation." Equally important: "Correlation does not imply confounding."
 
I'm just reading "The Book of Why". It explains, among many other things, why it is actually true that beauty and intelligence can be negatively correlated, provided that we consider a population with a common feature, such as success in show business.
 
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What sort of prerequisite in typical statistics is assumed? Is the list in increasing order of difficulty/advanced-ness?
 
Muu9: Great question! Here are the prereqs as I see them:

The Book of Why: high school statistics.

Causal Inference in Statistics: A Primer: the usual calculus sequence (including multivariable) followed by mathematical statistics.

Causality: Models, Reasoning, and Inference: This is extremely difficult, and I have not read it. I recommend the usual calculus sequence, mathematical statistics, Bayesian statistics (to the level of Gelman's BDA), and Bayesian networks before attempting this book.

These three books constitute the Directed Acyclic Graph approach. The other main approach, the Potential Outcomes Framework, is headed up by Donald Rubin. The main book here is

Causal Inference for Statistics, Social, and Biomedical Sciences: An Introduction: Prereqs appear to be (I have not read this book) calculus, mathematical statistics, linear models, and design and analysis of experiments. Bayesian statistics wouldn't hurt.
 
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