Those sailors who had eaten: The reason is that polar bear livers do contain vitamin C.

“On the Inadequacy of the Partial”: The title refers to partial correlation, a standard method of controlling for a confounder that we discussed in Chapter 7.

Here is how to define the NIE: In the original delivery room, NIE was expressed using nested subscripts, as in Y(0,M). I hope the reader will find the mixture of counterfactual subscripts and do-operators above more transparent.

In that year researchers identified: To be technically correct it should be called a “single nucleotide polymorphism,” or SNP. It is a single letter in the genetic code, while a gene is more like a word or a sentence. However, in order not to burden the reader with unfamiliar terminology, I will simply refer to it as a gene.