My coauthors and I are working on a paper using the Economic Freedom of the World and 19 countries (sample cannot be increased because it is focused on a specific Region). The number of years is 19, then our sample is relatively short. We are trying to design a "non-orthodoxal experimental review", and apply diff-in-diff, but: 1) we do not have a specific treatment year, countries can be treated or not treated during all the period sample (treatment is if economic freedom score decreased, then country 1 can be treated in year 3, 4, 8, 10 (if its economic freedom score decreased those years) and not-treated in the other years that its economic freedom score did not decrease); 2) we are using an interaction model, my two interaction terms are treatment (1 if decreased the score of economic freedom, 0 otherwise), and intensity (the % variation of the economic freedom score), and other controls. We have presented in some seminars and conferences the research progress and early results of this paper but suggestions just focus on the "size of the sample", which we know could be a caveat but as I said the research intention is just the Region, the early results are significant and show the expected signs. We have not received suggestions on our "non-orthodoxal experimental review" (different treatment years, countries that can be treated or not in different years, our interaction model specification, etc...) My specific question is: Does anybody could give us some insights or suggestions on the methodology and how to respond convincingly that increasing the sample size is not an option for this research.
