The Organization of Chipped-Stone Economies at Piedras Negras ...

used, they probably had a lesser exchange value. Second-series blades, third-series
rejuvenation blades, and rejuvenation pressure-blades removed from the distal end of the
core were all useful cutting and scraping tools, but since they feature irregular cutting
surfaces and overall morphology, they may not have been exchanged away from the
original area of their production. Exhausted blade-cores and blade-core fragments also
are not direct evidence for production activities, but the assumption is that these debitage
types likely remained near their original locus of manufacture.
Finally, third-degree production evidence consists of percussion flakes and
blades, first-series pressure blades and flakes, and other small and unused core-
maintenance flakes. These debitage types represent the earliest stages of blade-core
preparation, or little-used flakes and ribbon blades that probably were not valued as tools.
Since similar debitage types have been found in large production dumps from the Maya
area, such as the Ojo de Agua deposit studied by Clark and Bryant (1997) and the
production deposit from site 272-136 of the BRASS survey in Belize studied by Marc
Hintzman (2000), they are considered to be good markers for production activities.
The average production value for a given excavated operation, which in most
cases represents excavations carried out in a single residential group, is used to identify
that operation, and by extension, that residential group, as a more or less likely
production locale. Using simple parametric statistics I calculated the standard deviation
of average production values per operation (i.e., residential group) during a given time
period. I then produced a z-score for each household and removed residential groups that
fell below 90% probability. In this way, I discarded residential groups that had
88