Your grandmother may be able to get away with estimating measurements for her famous marinara sauce, but when it comes time to bake a cake, you can almost guarantee that she measures everything out with some precision. That’s because baking is more sensitive to proportions and process than other forms of cooking.
And just as we standardize cake recipes using conventions such as tablespoons, cups, and kilograms, we also standardize beer recipes. Process is, however, not generally replicable, which means that each brewer has to make adjustments according to the strengths and limitations of his or her own system.
One of the parameters that’s different for every brewer is efficiency. Further complicating the matter is that there are several kinds of efficiency. At their core, all forms of efficiency quantify how much sugar you get out of your grain, relative to how much is actually there for the taking.