DAACS Seriation Method
DAACS has developed an uniform set of methods to infer intra-site chronologies for all of the sites included in the Archive. These methods, which include frequency-seriation and correspondence analysis, were developed by DAACS (see Neiman, Galle, and Wheeler 2003 for technical details). The use of common methods for all sites in the Archive is designed to increase comparability among temporal phases at different sites. The methods and the phase assignments they produced are summarized below. For some sites, the original excavators developed intra-site chronologies and where these exist, they are included on the Background page for the site. Archive users may also use the Mean Ceramic Date queries provided on the DAACS query page to calculate MCDs for individual contexts or features.

Seville House 15 Chronology
This section summarizes the frequency-seriation based chronology for House 15 at Seville Plantation. At House 15, DAACS seriated ceramic assemblages with more than 5 sherds from individual excavated contexts. Please note that at House 15, ware types, not mean-ceramic-date types, were used in the frequency seriation, correspondence analysis, and in developing the dates for each occupational phase. Please click here for more information on the differences between ware types and mean-ceramic-date types.

DAACS computed the frequency of ceramic ware types in each individual context. The seriation chronology is derived from a correspondence analysis of the ware-type frequencies. Seriated contexts were assigned to four phases. Phases are groups of assemblages that have similar correspondence-analysis scores and are therefore inferred to be broadly contemporary. Phases assigned by DAACS have a P-prefix that precedes the phase number (e.g. P01 equals Phase 1).

The stratigraphic relationships among contexts are summarized in the Harris Matrix for House 15. Phase assignments from the seriation are shown on the Harris Matrix in color, facilitating comparison of the seriation chronology and the stratigraphic chronology of the site.

Seville House 15 Phases
Based on the correspondence analysis, DAACS divided the House 15 occupation into four phases. Ware-type mean ceramic dates with start dates of 1600 were used to compute MCDs for each phase. The MCDs for the four House 15 phases are given in the table below.

The table also includes three estimates of the ceramic TPQ for each phase. The first TPQ estimate is the usual one – the maximum beginning manufacturing date among all the ware-types in the assemblage. The second estimate -- TPQp90 -- is the 90th percentile of the beginning manufacturing dates among all the sherds in the assemblage, based on their ware-types. The TPQp95 provides a robust estimate of the site's TPQ based on the 95th percentile of the beginning manufacturing dates for all the artifacts comprising it. These last two TPQ estimates are more robust against excavation errors and taphonomic processes that might have introduced a few anomalously late sherds into an assemblage.

Phase MCD TPQ TPQp90 TPQp95 Total Ceramic Count P01 1751 1820 1775 1775 1715 P02 1777 1830 1775 1820 2591 P03 1815 1840 1820 1820 907 P04 1863 1840 1820 1820 199

A Seriation Chronology for Seville House 15
The following table presents a seriation chronology for House 15. We use the indefinite article to signify that it is not the only chronology possible, nor even the best one possible.