1. A comment on an interesting paper: Perhaps the easiest type of paper to write is a comment on an existing paper. Such comments often turn out to be more important than the original work. Think about flaws in some paper that you read. Is there selection bias? Has the author left out a potentially crucial variable? One year a student noticed a footnote in a paper by on the reading list that said one observation had been left out of the figure because it was so large relative to the others. This same extreme observation was included in the empirical analysis. The student got the data and showed that his results depended crucially on this one observation.

2. A comparison of past events with present events: Few economic events have no historical antecedents. If there is a modern development you are interested in, you could look for its historical roots or counterparts. For example, so much has been written about the rise of the Internet and the revolution in communication in the 1990s. How do these developments compare to the rise of the telegraph and the telephone? The rise of TV and radio? Were there similar changes in investment in the 1890s as in the 1990s? One year a student looked at how the U.S. experience with free banking in the mid-19th century compared to some of the developments in European currency relationships in the 1990s.

3. Analysis of an interesting source: While it is not a good idea to let data availability drive your topic, it is perfectly reasonable to let serendipity play a role. Have you come across an unusual source in the library or during your undergraduate years? Is there an interesting question that this source could be used to answer? One year a student came across the catalogs for the 1851 World’s Fair. She had the idea that these descriptions of what each country exhibited could be used as a measure of innovation. She wrote a paper looking at the industrial composition of innovation across countries. (It turned into her dissertation, and MIT's Sloan School has now hired her.)

Another student was looking through newspapers from San Francisco in the 1870s. He found many classified ads that read something like: "Wanted — man to work in store and loan store $1000." This student wondered why companies would tie employment and loans. He wrote a paper investigating whether ads such as these were a sign of credit market imperfections or a way of ensuring worker loyalty and honesty.

4. A new test of an old debate: A very successful way to write papers follows the example of Peter Temin’s article on British trade during the Industrial Revolution found on this course's reading list. Take some interesting debate in economic history and come up with a clever, alternative way of testing it. Usually, such a test involves using a new type of data. For example, if everyone has been using quantities, think about a way to use prices. An example of this type of paper involves the debate over how business cycles have changed over time. One researcher suggested that instead of fighting over very imperfect estimates of real GDP, one could look at stock prices as an indicator of the volatility of the macroeconomy.

5. A Natural Experiment: Just as one should be on the lookout for interesting sources, one should also be thinking about interesting events. History is full of natural experiments--some weird tax is passed, a war is fought, a new regulation is imposed. Often such experiments can be used to answer crucial

questions in economics--for example, what the changing speed with which liberty ships were built during World War II tells us about the size of learning-by-doing effects.