Cochrane’s Writing Tips
A condensed summary of John Cochrane’s Writing Tips for Ph.D. Students (2005). The advice is his and the wording here is a paraphrase, so read the original for his examples.
Organization
- Find the one central, new contribution of your paper and write it down in a single concrete paragraph: state the result itself, not that you found interesting results.
- Readers skim. Put the main result first and fill in detail afterwards, as a newspaper does, instead of building to a punchline in the last table.
- Leave out the story of how you got there and the things that did not work.
Abstract and introduction
- Keep the abstract to 100–150 words. Say concretely what you find, and leave other literature out of it.
- Open the introduction with your contribution, not with philosophy, the literature, or policy motivation.
- Give the fact behind each claim, such as the regression and the number, not just the conclusion it supports.
- About three pages is enough for an introduction. A roadmap paragraph is optional.
Literature review
- Explain your own paper before comparing it with others: readers cannot judge the difference until they understand your contribution.
- Keep the review short and set apart. Focus on the two or three closest papers and on giving credit where it is due.
- Be generous. Your paper does not need everyone else to be wrong in order to be interesting.
Body of the paper
- Nothing should come before the main result unless the reader needs it to understand that result.
- In an empirical paper, include only the theory the empirics need, and write down the specific model you take to the data rather than a general one.
- Lead with the main result, follow it with the graphs and tables that show why it holds, then a limited set of robustness checks.
- Keep the conclusion short: no full restatement, no research agenda, no speculation.
- Move extra robustness checks, extensions and the general model to an appendix, online if need be.
Writing
- Keep it short. Every sentence should earn its place, and a finished paper should rarely need more than about 40 pages.
- Say each thing once. Phrases like “in other words” usually signal a repeat.
- At every level, first say what you do, then why, then how it compares with the alternatives.
- Frequent pointers forward and back, such as “as we will see” or “recall that”, suggest the material is in the wrong order.
- Document your work so that another student could reproduce every number from the paper and its appendix.
- Simpler is better. Less math and simpler methods make a paper more convincing, not less impressive.
- Keep track of what the reader already knows. Most students assume far too much.
Footnotes, tables and figures
- An aside that matters belongs in the main text, and one that does not should go. Footnotes are for material most readers can safely skip.
- Give every table and figure a caption a skimming reader can understand on its own. For a regression, include the equation and the dependent variable.
- Discuss every number you show. If it is not worth a sentence, drop it from the table.
- Report two or three significant digits, in units that give readable numbers.
- Label axes, define every symbol in the caption, and choose line styles that still show up when printed.
Style
- Use the active voice and take responsibility for your claims. “I” is fine on a sole-authored paper.
- Prefer the present tense, and keep tenses consistent within a paragraph.
- Write plain subject–verb–object sentences with few clauses, short words and little jargon.
- Do not praise your own results with adjectives; let readers judge them.
- Cut empty openers such as “it should be noted that” and just make the point.
- Follow “this” with a noun, so the reader knows what it refers to.
- Give Greek letters names as well as definitions, and remind readers what they stand for.
- Describe a model’s structure directly; keep “assume” for claims about the real world.
- Spell out authors’ names, skip the opening quotation, and use italics sparingly.
Empirical work
- Identification comes first. Explain what moves your right-hand-side variable, what makes up the error term, and why the two are unrelated.
- Explain why your instruments move the regressor but not the error, and know when a variable belongs as an instrument rather than a control.
- For every estimate, say which variation in the data drives it, for example within firms over time or across firms.
- Ask whose behavior you are modeling, so you do not mistake a supply curve for a demand curve, and rule out reverse causality.
- Use few controls. Do not control for the channels through which your variable works, and be suspicious of a very high R².
- Show the stylized facts behind your estimates, not just test statistics.
- Report economic magnitudes as well as statistical significance, and a standard error for every important number.
Seminars
- Skip the motivation, literature review and preview of results; start with the main result.
- Put equations, tables and graphs on slides rather than your script, and leave each slide up long enough to absorb.
- Listen to the whole question and pause before answering. Keep paper at hand to note what to change.
- Err toward simplicity: audiences absorb far less in one sitting than presenters expect. Speak slowly and clearly, and finishing early is fine.
Why it matters
- Economics papers are essays, and good economists spend much of each project on the writing. Cochrane points to Zinsser’s On Writing Well and McCloskey’s Rhetoric of Economics for more.