If you are editor of an Economics journal that seeks to improve and come across a paper entitled "What Makes a Great Journal Great in Economics?", you read it expecting some great recommendations, for example on how to attract great papers, generate good readership that will cite the articles and how to get established authors interested in submitting.
I supposed this is what Chia-Lin Chang, Michael McAleer, and Les Oxley were out to do, and what a disappointment it is. They take Thomson Reuters ISI Web of Science citation data, torture it in all sorts of innovative ways and come to the conclusion that for the top 40 journals in Economics, looking at the 2-year impact factor gives a distorted picture. First, how does this answer the question in the title? Second, it is already well known that these impact factors are flawed and only appreciated by publishers. Indeed, they encourage self-citations by journals, whose editors strategically require from authors to cite other articles. The two year window is ridiculously short for Economics. And the choice of journals that are indexed is difficult to follow.