Why are economic journal articles so long?

Seriously.

I've been reading a lot of (hard) scientific studies for my current dissertation chapter and it is striking how concise they are. The majority of published articles, at least the ones that I have come across, are typically no more than 4-6 pages in length. The pattern holds especially true for the most prestigious journals like Nature, Science or PNAS.

In contrast, your average economic article is long and getting longer. [Note: New link provided.]

Now you could argue that science journals achieve this feat by simply relegating all of the gritty technical details and discussion to the supplementary materials. And this is true. For a good example, take a look at this article by Estrada et al. (2013).[*] The paper itself is only six pages, while the supplementary material is over 40 pages long. Equally as telling is how similar this supporting information is to the working paper that the final article is apparently based upon.

To be honest, I don't really see how this can be a bad thing. It is primarily the job of the editors and referees to vouch for the technical merits and internal consistency of a published study. Regular readers are mostly interested in the broad context (i.e. significance of the research) and the actual findings. As much as it is important to make the technical details -- and data! -- available to those who want to go through them, the clutter largely detracts from the key messages. I'm also willing to bet good money that many (most?) people currently just skip through the entire mid-section of your typical economics paper anyway, concentrating on the introduction, results and conclusion.

So, is this a weird case of physics envy, where economists feel the need to compensate for lack of quality through quantity? Or does it say something special about the nature of economics, where the limited extent of true experimental data makes methodology more precarious and prone to bias?

Either way, do we really lose anything by making economic journal articles much shorter and saving all the technical details for the supplementary materials?

PS - Yes, I know that most economic journals already reserve a lot of information for the technical appendices. I'd also say that a number of the top journals (e.g. AER) are pleasantly readable -- perhaps surprisingly so for outsiders. But we're still a long way off what the sciences are doing.

UPDATE: It just occurred to me that the frequency of publication plays a reinforcing in all of this. Nature, Science and PNAS are all issued on a weekly basis. The top economic journals, on the other hand, are typically only bi-monthly (at best) or quarterly publications. The higher volume of science publications encourages concise articles for pure reasons of practicality, as well as readability.

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[*] The authors argue that climate data are better viewed as statistical processes that are characterised by structural breaks around a deterministic time trend... i.e. As opposed to non-stationary stochastic processes comprising one or more unit roots. (This is important because it has implications for the ways in which we should analyse climate data from a statistical time-series perspective.) In so doing, they are effectively reliving a similar debate regarding the statistical nature of macroeconomic time-series data, which was ignited by a very famous article by Pierre Perron. Perron happens to be one of the co-authors on the Estrada paper.