So for those who are drawn to such things, I've created a second version of the quiz. This is a parallel form to the earlier quiz, with all new questions but constructed with approximately the same balance of question types and (I hope) difficulty.
This quiz tests your explicit knowledge of grammatical concepts. That is, unlike some other tests, you need to know and apply technical vocabulary relating to grammar in order to answer most of the questions. It tests a wide range of concepts, from those commonly taught in primary school to those that are largely the province of linguists. I have tried hard to avoid questions where the "correct" answer changes depending on what grammatical theory one applies. (If you notice any such ambiguities, please drop me a line.)
The questions generally become more difficult as you go through the quiz, and overall, most people, even college-educated adults, will find it challenging. The median score on the earlier version of this quiz was 69%, and less than 5% of people scored above 90%.
Some questions ask you to identify or analyze different constituents of written English by using technical grammatical vocabulary. Other questions ask you to apply your knowledge of grammatical terms in identifying potential errors.
Unless otherwise indicated, the term "error" is used to mean that the language in question does not conform to the requirements of contemporary, standard written English as it is widely understood by English teachers and editors.