And Abraham drew near: As before, I have used the King James translation but made small changes to align it more closely with the Hebrew.

The ease and familiarity of such: The 2013 Joint Statistical Meetings dedicated a whole session to the topic “Causal Inference as a Missing Data Problem”—Rubin’s traditional mantra. One provocative paper at that session was titled “What Is Not a Missing Data Problem?” This title sums up my thoughts precisely.

This difference in commitment: Readers who are seeing this distinction for the first time should not feel alone; there are well over 100,000 regression analysts in the United States who are confused by this very issue, together with most authors of statistical textbooks. Things will only change when readers of this book take those authors to task.

Unfortunately, Rubin does not consider: “Pearl’s work is clearly interesting, and many researchers find his arguments that path diagrams are a natural and convenient way to express assumptions about causal structures appealing. In our own work, perhaps influenced by the type of examples arising in social and medical sciences, we have not found this approach to aid the drawing of causal inferences” (Imbens and Rubin 2013, p. 25).

One obstacle I faced was cyclic models: These are models with arrows that form a loop. I have avoided discussing them in this book, but such models are quite important in economics, for example.

Even today modern-day economists: Between 1995 and 1998, I presented the following toy puzzle to hundreds of econometrics students and faculty across the United States:

Consider the classical supply-and-demand equations that every economics student solves in Economics 101.

1. What is the expected value of the demand Q if the price is reported to be P = p0?

2. What is the expected value of the demand Q if the price is set to P = p0?

3. Given that the current price is P = p0, what would the expected value of the demand Q be if we were to set the price at P = p1?

The reader should recognize these queries as coming from the three levels of the Ladder of Causation: predictions, actions, and counterfactuals. As I expected, respondents had no trouble answering question 1, one person (a distinguished professor) was able to solve question 2, and nobody managed to answer question 3.

The Model Penal Code expresses: This is a set of standard legal principles proposed by the American Law Institute in 1962 to bring uniformity to the various state legal codes. It does not have full legal force in any state, but according to Wikipedia, as of 2016, more than two-thirds of the states have enacted parts of the Model Penal Code.