The introduction to a paper or seminar, and the overall structure of the paper or seminar, can be usefully thought of as efforts to win over a skeptical referee (something that will harry you for the rest of your professional career).

Imagine a referee who asks the following set of questions:

What is the question that you want to answer?

• If it takes you more than a few sentences to answer this question, then you likely have not thought about it hard enough. There is an old story of Blaise Pascal apologizing for writing a long letter because he didn't have time to write a short one. This is the right spirit.

• The kind of answer that one provides to this depends very much on the problem you consider. The kinds that you should contemplate include:
• There is a a real-world problem that is quantifiably important, potentially with policy implications, for which this will provide insight.
• There is a significant literature that has addressed this problem, so that the profession has demonstrated its interest.
• Existing literature inadequate or incomplete in various respects.
• In selecting a topic, remember Summers’ Law: “It takes as much time to answer a minor question as an important one.” So you may as well choose important questions.

• Again, if you cannot answer this concisely -- a few sentences at most -- then probably you have not thought about it hard enough.
• Often it is very helpful to note a couple or a few papers that are closely related, and be able to say what is distinctive about your contribution relative to those mentioned.

• You should be able again to describe in just a few sentences what experiments you are going to perform (empirical or theoretical), and what the major conclusions will be.

• No piece of work is the final word on a problem. This is your chance to do a bit of selling, but also to acknowledge that there are problems that remain unresolved (lack of data, future work, etc.).

• This is the bottom line. What have we really learned? You must have an answer.