Friday, August 28, 2015

New Article: "Quantitative analysis of Munsell color data from archeological ceramics" Open Access!

My former student Lana Ruck and I have published an article on how to mathematically analyze Munsell color data. Although we use data from archaeological ceramics as our prime example, the method would work with any body of Munsell color data that was collected to address a hypothesis. The colors could be from soils, minerals, leaves, flowers, birds, and so forth, and the method would still work. We're so convinced that this article will be of wide interest that we paid for open access.

The idea is that you convert the Munsell readings to spatial coordinates in the Munsell color space and then perform spatial or statistical analyses on the coordinates, which are interval scale variables. For the kinds of hypotheses I wanted to test--whether the ceramic colors from one houselot or cluster of houselots were the same as those from another--I decided that logistic regression was probably the right technique because:
  • the dependent variable (the provenience, i.e., the houselot of cluster of houselots) was a categorical variable; and
  • the data were demonstrably non-normal, thus eliminating linear discriminant analysis.
I've been struggling with the issue of how to analyze this kind of data ever since I got back from Mayapan in 1992 or 1993 with thousands of Munsell observations and realized that I didn't know how to perform statistical tests on them. My best guess is that I finally figured out how to do it right, at least in theory, around 2006 or 2007, but it wasn't until a couple of years ago that Lana came along and mastered the logistic regression.

Apparently, the real lesson here is that if you think about something for 20 years, you just might figure out the answer, although I hasten to point out that during those 20 years I studied quantitative techniques pretty intensively.  I wasn't just sitting on the beach pondering the problem solely in thought; I was actually educating myself--howsoever unsystematically--about the general topic of mathematics in archaeology. Nevertheless, there is a push among university administrators to systematize and quantify scientists' goals and productivity. So, if I put down on my annual assignment that I'm going to study how to analyze Munsell colors, presumably I'm expected to produce the article in the year it's listed. If you take into account how long it took to devise the original research design, excavate the artifacts, and record the Munsell colors, this article has been in the works for 25 years! Should I submit a 25-year plan as part of my annual assignment? If I do, I can probably say anything I want because I'll almost certainly be dead in 25 years.

Here is the reference, linked to the article:

Ruck, Lana and Clifford T. Brown (2015). Quantitative analysis of Munsell color data from archeological ceramics. Journal of Archaeological Science: Reports 3:549-557. 

Just in case the link doesn't work for any reason, here is the URL:


As always, comments welcome.

Sunday, August 23, 2015

Soils of Latin American and the Caribbean

For those of you who, like me, sometimes work in areas of Latin America or the Caribbean where soil data are rare, difficult to obtain, unpublished, or simply unavailable, there is a very useful new work that I'm finding helpful: Atlas de suelos de América Latina y el Caribe.

It includes complete maps of the region, although they are published at a scale of 1:3,000,000 which can make identification of the location of individual sites difficult. Nonetheless, I have found it an extremely useful work. Not only are the maps helpful, but the soil taxonomy is explained with great simplicity and clarity, which is convenient for an archaeologist with no meaningful training in soil science.

Here is the citation suggested in the front matter of the document:

Gardi, C., Angelini, M., Barceló, S., Comerma, J., Cruz Gaistardo, C., Encina Rojas, A., Jones, A., Krasilnikov, P., Mendonça Santos Brefin, M.L., Montanarella, L., Muñiz Ugarte, O., Schad, P., Vara Rodríguez, M.I., Vargas, R. (eds), 2014. Atlas de suelos de América Latina y el Caribe, Comisión Europea - Oficina de Publicaciones de la Unión Europea, L-2995 Luxembourg.

Even better, it's available online at: