The Non-Diagnostic Sherd Problem: Lessons from Jeddito Yellow Ware Typology

THE NON-DIAGNOSTIC SHERD PROBLEM: LESSONS FROMJEDDITO YELLOW WARE TYPOLOGY

Wesley Bernardini

Abstract

Although ceramic types are applied most commonly to sherds (simply because of

their abundance), most typologies have been derived at least in part from patterns

of attribute covariation on whole vessels. As a result, one typological concern is

the “non-diagnostic sherd problem,” where only a fraction of the sherds deriving

from a whole vessel share all of the attributes of that vessel. This paper assesses the

severity of the non-diagnostic sherd problem for Jeddito YellowWare polychrome

sherds, demonstrating that it may cause up to half of the sherds from some poly-

chrome vessels to be incorrectly typed. Implications for chronology and social

dynamics are discussed, and a preliminary correction for the non-diagnostic

sherd problem is offered.

Resumen

A pesar de que las clases cerámicas frecuentemente se aplican a tiestos (sobre todo por

razón de su abundancia), la mayoría de las tipologías se derivan en parte de atributos con-

currentes en vasijas enteras. Así queda la cuestión de “el problema de tiestos no-diagnós-

ticos”, en lo cual sólo una minoría de los tiestos de una vasija manifiestan todos los

atributos de la vasija. El presente artículo valora la gravedad de “el problema de tiestos

no-diagnósticos” acerca de los tiestos polícromos de Jeddito Yellow Ware, y demuestra

que el problema ya mencionado resulta en una clasificación equivocada de hasta la

mitad de las piezas polícromas. Las consecuencias en fechar la cerámica son tratadas y

propone una corrección preliminar.

Introduction

Most archaeologists recognize that ceramic typologies apply differ-ently to sherds than they do to whole vessels. Although ceramic

types are applied most commonly to sherds (simply because of their abun-dance), most typologies have been derived at least in part from patterns of attri-bute covariation on whole vessels. This disjuncture is potentially problematic, inpart because the unit of production and use (the whole vessel) is not the same asthe unit of analysis (the sherd). Of principal concern in this paper is the fact thatonly a fraction of the sherds deriving from a whole vessel will typically share allof the attributes of that vessel—what will be termed here the “non-diagnostic sherd

KIVA: The Journal of Southwestern Anthropology and History, Vol. 79, No. 2 (Winter 2014), pp. 205–227.Copyright © 2014 Arizona Archaeological and Historical Society. All rights reserved. 205DOI 10.1179/0023194014Z.00000000020

problem.” As a consequence of this fact, some fraction of sherds from a wholevessel will be incorrectly typed, and some will be untypeable.

The primary analytic risks stemming from the non-diagnostic sherdproblem are under-counting of the types to which they rightly belong, and theover-counting of the types to which they are mis-assigned. There are bothchronological and social implications of such errors. First, if sherds lacking adiagnostic attribute are systematically misclassified as an earlier or later type,ceramic cross-dating will be skewed too late or too early. Second, because thepresence or absence of particular types of pottery is often interpreted in socialterms, miscounted types can affect analyses of social dynamics such as status,trade, and migration. For example, a primary point of contention in theChavez Pass/Grasshopper debate revolved around whether the absence of poly-chromes on small sites reflected restricted access to elite goods or chronology(Upham et al. 1981). Similarly, the presence of Pottery Mound Polychromehas been argued to mark the presence of groups with social/religious ties toHopi (Eckert 2008). In both cases, it would be critical to control for the non-diagnostic sherd problem before reaching final conclusions about socialprocesses.

The non-diagnostic sherd problem is recognized by ceramic analysts (e.g.,Wilson and Blinman1995) but is not thought to pose serious problems in mostcases since 1) the multiple types that result from a whole vessel tend to be “adja-cent” in time, and 2) the mistyped sherds should be a minority of the vessel,both of which limit counting errors. The non-diagnostic sherd problem,however, can be more serious for certain kinds of vessels. Most problematicare vessels for which one or more critical diagnostic attributes are present ononly a small portion, resulting in sherd assemblages in which only a minorityof sherds can be “correctly” typed. I refer to vessels in this category as “rare attri-bute types” (RATs). RATs are especially prevalent among polychrome vessels and/or vessels with relatively sparse or localized designs, including utilitarian vesselswith diagnostic surface treatments confined to a narrow portion of the vessel(e.g., neck banding). Late Jeddito Yellow Ware (JYW) types (ca. A.D. 1385–1630) exhibit these RAT qualities (polychrome and sparse designs) (Figure 1),and thus are likely contributing non-trivial amounts of error to type frequencyestimates.

The extent of the non-diagnostic sherd problem in late Jeddito YellowWare sherd assemblages is explored first through a comparison of wholevessel-to-sherd type frequencies. Then, an analysis of simulated sherd assem-blages from actual whole Jeddito Yellow Ware vessels is used to suggest amethod by which sherd frequencies may be corrected to account for mistypednon-diagnostic sherds. The methods developed should be applicable to otherRAT ceramic types which share the non-diagnostic sherd typological problem.

WESLEY BERNARDINI206

Jeddito Yellow Ware

The production of Jeddito Yellow Ware pottery began around A.D. 1300 andtook place exclusively in the Hopi Mesas region of Arizona (Bernardini 2005;Bishop et al. 1988) (Figure 2). All Jeddito Yellow Ware shares a distinctivelyyellow, well-fired paste resulting from coal firing (Block 1985), apparently aunique technological attribute within the Southwest. Although a substantialnumber of whole Jeddito Yellow Ware pots exist in museum collections, mostJeddito Yellow Ware recovered in contemporary fieldwork is encountered assherds. This is due largely to the reduced role of excavation in southwestern aca-demic field schools in the post-NAGPRA environment, and the fact that mostarchaeological sites likely to contain Jeddito Yellow Ware are in the northernSouthwest, away from the hotspots of contract archaeology.

The existing Jeddito Yellow Ware typology focuses primarily on four vari-ables thought to be temporally sensitive (Hays 1991; Lyons and Hays-Gilpin2001:151; Smith 1971): 1) abundance of temper; 2) color of paste; 3) paintcolor(s), and 4) design style. In general, earlier JYW types have more temper,darker paste color, bichrome (black) rather than polychrome (black and red)paint, and geometric designs; later types have less temper, lighter paste, poly-chrome paint, and figurative designs (LaMotta 2006). With the exception ofpaint colors, however, all of these attributes vary along a continuum oroverlap to such an extent that it has proven difficult to find clear lines alongwhich one or more attributes change with sufficient clarity to warrant a type dis-tinction. This is especially true when typing sherds as opposed to whole vessels.At a recent Jeddito Yellow Ware ceramic conference at the Museum of Northern

FIGURE 1. Illustration of the non-diagnostic sherd problem in a Sikyatki Polychrome vessel.

LESSONS FROM JEDDITO YELLOW WARE TYPOLOGY 207

Arizona, participants agreed that despite the general validity of trends in temperdensity and paste color at the level of the assemblage, these patterns werevariable enough across fourteenth-century JYW types to raise questions about

FIGURE 2. Sites and regions mentioned in the text.


their applicability to individual sherds (Kelley Hays-Gilpin, personalcommunication).1

Similarly, stratified deposits from Homol’ovi I and Homol’ovi II revealthat the geometric versus figurative design style change, once thought to a berelatively rapid and clean transition in the later A.D. 1300s, actually involves sig-nificant overlap, with “early” style geometric designs persisting at least into thelate fourteenth century if not beyond (see Adams, this volume). Stratified depos-its at Homol’ovi I and Homol’ovi II demonstrate that geometric designs can onlybe pegged to specific portions of the fourteenth century if other attributes arevisible such as the banding line (see below) and overall area of decoration,again limiting the utility of these attributes for the classification of sherds.

LaMotta’s work on Jeddito Yellow Ware (LaMotta 2006) has revealed thatmeasurements involving the sub-rim banding line that encircles the interiordesign field are time-sensitive, and correlate to some extent with design stylechanges. These measurements offer great promise as chronological tools at thelevel of the assemblage, but again do not appear to be appropriate for the classi-fication of individual sherds (both because of variation around the banding-linetrends and because few rim sherds are large enough to show both the bandingline and a sufficient portion of the decorated area).

Within the yellow ware sequence a primary distinction is made betweenbichromes (vessels with only black or brown paint on a yellow paste) and poly-chromes (vessels with black paint plus red or white paint). Of the attributes usedin the Jeddito Yellow Ware typology, paint color is the one of the few that can bereliably used to type individual sherds (as opposed to characterizing assem-blages). In contrast to the attributes discussed above, paint color is useful fortyping sherds because it exhibits a clear, presence–absence quality. The initialappearance of red paint is also clearly time-sensitive, with stratified depositson both Hopi and Homol’ovi villages and patterns of association with cross-dated ceramics elsewhere placing the beginning of polychrome designs onJYW around A.D. 1385 (LaMotta 2006; Hays 1991; Benitez 1999). All JedditoYellowWare produced prior to 1385 is bichrome; the exception, Bidahochi Poly-chrome, contains black and white paint, dates to the early to mid-1300s, and isrelatively rare.2

The most common Jeddito Yellow Ware polychrome is Sikyatki Poly-chrome, which features the use of both black and red paint on a yellow paste.The proportion of Sikyatki Polychrome in stratified deposits also clearlyincreases through time (LaMotta 2006). The production of Sikyatki Polychromecontinued until approximately A.D. 1630. There are two primary variants ofSikyatki Polychrome: Middle Sikyatki Polychrome (ca. A.D. 1385–1425/1450)has large massed areas of red filling in geometric black designs; Late SikyatkiPolychrome (ca. A.D. 1425/1450–1630) features life forms and free treatment,with red solid areas outlined by black lines.3


The importance of paint colors for typing Jeddito Yellow Ware sherdsmakes bichrome/polychrome distinction of primary interest in the JedditoYellow Ware typology. The presence of Sikyatki Polychrome, for example, iscommonly used to establish terminus post quem and terminus ante quem datesfor site occupations. The presence of Sikyatki pottery also has social significancein terms of the spread of Sikyatki style (across a range of media) and the ritualconcepts and practices with which it was associated (Hays-Gilpin and LeBlanc2007).

DOCUMENTING THE NON-DIAGNOSTIC SHERD PROBLEM

The non-diagnostic sherd problem applies especially to polychrome vessels likeSikyatki Polychrome. Because a minority of sherds from these polychromevessels contains the diagnostic attribute of red paint, a significant number ofthe resulting sherds will be mistyped as bichromes. The problem should be exag-gerated in later sites with greater proportions of polychrome whole vessels.

Data

To evaluate this phenomenon, data were assembled from published sources andfrom the Yellow Ware Online Database (http://yellowware.museumhosting.com/index.php). Vessels in this online database were photographed as part ofthe Hopi Iconography Project (originally known as the Southwest MuralProject), a collaborative effort between the Hopi Tribe and researchers at theMuseum of Northern Arizona and the Peabody Museum, Harvard University.The vessels in the database are housed in 17 museums across the UnitedStates4 as well as private collections, totaling 5,445 vessels or vessel fragments.The Yellow Ware Online Database is now hosted by the University of Redlands;access is currently restricted to protect the image copyrights of the curating insti-tutions, but can be provided to interested researchers by contacting the author.

While the Yellow Ware Online Database contains a relatively comprehen-sive collection of the whole JYW vessels in the United States, it is not fully repre-sentative of JYW variability. A particular weakness is the scarcity of whole vessels(N = 5 pre-contact specimens) from Third Mesa villages. Thus, the village ofOrayvi, one of the largest and most important villages of both pre-contact andpost-contact Hopi society, is almost completely unrepresented in the wholevessel sample. Antelope, First, and Second Mesas are all relatively well-represented with 300–500 vessels each. The majority of vessels (N = 1444),however, lack any provenience, a consequence of the era (late 1800s/early1900s) and manner (looting/poorly documented archaeology) in which theywere collected.


http://yellowware.museumhosting.com/index.php






Vessel Versus Sherd Proportions

To estimate the magnitude of the non-diagnostic sherd problem in sherd assem-blages containing polychrome Jeddito Yellow Ware, proportions of wholevessels and sherds were compared from three sites for which both wholevessel and sherd assemblages were available from published sources: Homol’oviII (representing an “Early” site); Kawàyka’a (representing a “Middle” site); andlate contexts at Awat’ovi (representing a “Late” site) (Tables 2–4). Sample sizeis an issue in these data, especially for whole vessels from Awat’ovi whereonly five are known from late contexts. Additionally, the context of the wholevessels and the sherds differ (the whole vessels come largely from burialswhile the sherds come from a mixture of room, midden, and surface contexts),although a comparison of bichrome and polychrome frequencies in burial andnon-burial contexts using the Yellow Ware Online Database found no differ-ences in frequency (both were 89 percent burial contexts, 11 percent non-burialcontexts).

With these caveats, the whole vessel and sherd assemblage data suggestthat the non-diagnostic sherd problem is affecting Jeddito Yellow Ware type fre-quencies in sherd assemblages (Tables 2–4). In all time periods, the proportionof bichromes to polychromes is higher for sherd assemblages than for wholevessel assemblages from the same site. This is inferably due to breakage of poly-chrome vessels on-site, a process which produced some non-diagnostic sherdslacking the diagnostic red color which were typed as bichromes. As expected,the distortion of the bichrome:polychrome ratio increases over time as the poly-chrome vessels became more common and number of polychrome vesselsbroken on-site increased.

SIMULATED SHERD ANALYSIS

To evaluate the non-diagnostic sherd problem more systematically, a second setof data was collected from the Yellow Ware Online Database. Data collectionwas restricted to bowls and jars (effigy vessels, ladles, miniature pots, andother uncommon forms were excluded). In addition, vessels were only includedin the study if they were more than 50 percent intact, and if the photograph wasof sufficient resolution. A total of 2,457 vessels meet these criteria (Table 5).From this total, a stratified random subset of 81 bichrome and Sikyatki Poly-chrome bowls was selected for the simulated sherd analysis (Table 6).

From each of these whole vessels, a sherd assemblage was simulated by“breaking” photographs of the whole vessels into sherd-sized pieces. This wasaccomplished by first drawing sherd-sized outlines onto a print of each bowl(e.g., Figure 3). To accomplish this, each pot was printed on an 8.5 in × 11 inpaper, and a grid of 3 cm× 3 cm boxes was drawn over the vessel (3 cm× 3 cm


TABLE 1. Decorative Attributes Characterizing JYW Types.

JYW Type Date rangeTemper Abundance(relative) Paste Color

Blackpaint

RedPaint Engraving

WhitePaint Design

AwatoviBlack-on-yellow

1300–1350

High Darkyellow1

X geometric

Awatovi/JedditoBlack-on-yellow

1325–1375

Medium Mediumyellow

X geometric

Jeddito Black-on-yellow 1350–1700

Low Lightyellow2

X figurative

Bidahochi Polychrome 1315–1400

Low Mediumyellow

X X geometric

Sikyatki Polychrome 1350–1700

Low Light yellow X X geometric early,figurative late

Awatovi Polychrome 1400-1625 Low Light yellow X X X geometric

Kawaika-a Polychrome 1450-1625 Low Light yellow X X X geometric

1 Munsell range 7.5YR to 10YR2 Munsell range 10YR to 2.5Y

WESLEY

BERNARDIN

I212

is a rough mean of Jeddito Yellow Ware sherd sizes from recent surface collec-tions of sites on the Hopi reservation). The grid followed the rim of thevessel. To account for the distortion of vessel surface area caused by an overheadphotograph of a curved bowl, the first row of boxes (starting at the rim) was only1 cm deep and the second row of boxes was only 2 cm deep.

The presence or absence of black and red paint was then tabulated for eachsimulated sherd. The results of this analysis are reported in Table 7 and summar-ized in Table 8. They reveal that 46 percent of the sherds from the averageSikyatki Polychrome bowl have only black paint and 22 percent have no paintat all, leaving only 32 percent of the sherds with the diagnostic decorative attri-bute (i.e., red paint) necessary to correctly type them as Sikyatki Polychrome.

TABLE 2. Type Frequencies, Whole Vessels vs. Sherds, Homol’ovi II.

Bichrome N (%) Sikyatki Poly N (%) Awatovi Poly N (%) Total N

Whole vessels 67 (95.7) 2 (2.9) 1 (1.5) 70

Sherds1 9034 (95.7) 82 (.009) 4 (.0004) 9454

1 Data from excavated and surface contexts (Hays 1991:Table 3.5).

TABLE 3. Type Frequencies, Whole Vessels vs. Sherds, Kawayka’a.

Bichrome N (%) Sikyatki Poly1 N (%) Awatovi Poly N (%) Total N

Whole vessels 123 (67.2) 57 (31.1) 3 (1.6) 183

Sherds2 3214 (77.0) 958 (23.0) ? 4172

1 Includes the Smith 1971 types “Sikyatki Polychrome” and “post-Sikyatki Polychrome.” Thelatter contains both “late” Sikyatki as well as literally “post” Sikyatki types, which were notdistinguished in Smith’s 1971 analysis.2 Data from all excavated Kawayka’a kivas (Smith 1971).

TABLE 4. Type Frequencies, Whole Vessels vs. Sherds, Late Contexts at Awat’ovi.

BichromeN (%)

Sikyatki Poly1

N (%)Awatovi/Kawàyka-a Poly

N (%)TotalN

Whole vessels - 2 (40.0) 3 (60.0) 5

Sherds2 452 (31.3) 882 (61.1) ? 1443

1 Includes the Smith 1971 types “Sikyatki Polychrome” and “post-Sikyatki Polychrome.” Thelatter contains both “late” Sikyatki as well as literally “post” Sikyatki types, which were notdistinguished in Smith’s 1971 analysis.2 Data from excavated Awat’ovi kivas 529, 788, and 908 (Smith 1971).


TABLE 5. Provenience of Whole Vessels in the Photographic Inventory.

Type

Area Bichrome Sikyatki Poly Kawàyka’a Poly Total

Antelope Mesa 247 102 5 358

Bidahochi 15 0 0 15

First Mesa 333 191 2 528

Homol’ovi 448 10 0 603

Off-Mesa 23 2 0 26

Second Mesa 213 102 2 318

Third Mesa 2 3 0 5

Unknown 472 273 12 779

Total 1753 683 21 2457

TABLE 6. Provenience of Whole Vessels Used in the Simulated Sherd Analysis.

Type

Site Mesa Bichrome Sikyatki Poly Total

Awat’ovi Antelope 1 5 6

Kawàyka’a Antelope 2 2 4

Kookopnyama Antelope 0 1 1

Old Walpi First 4 4 8

Sikyatki First 1 4 5

Walpi First 2 0 2

Homol’ovi I Homol’ovi 17 0 17

Homol’ovi II Homol’ovi 3 0 3

Unknown Mesa Redondo 1 0 1

Unknown near Chirovee/Tsirovee 0 1 1

Chukubi Second 4 0 4

Musangnuvi Second 15 1 16

Old Songoopavi Second 2 0 2

Unknown Unknown 5 5 10

Paimonivi Unknown 0 1 1

Total 57 24 81


Of the simulated sherds from Sikyatki Polychrome vessels containing onlyblack paint, roughly 30 percent have a banding line as the only painted decora-tion. Only 2 percent of the simulated Sikyatki Polychrome rim sherds have redpaint, and only 6.6 percent of the simulated sherds adjacent to the rim sherdhave red paint. Thus, the simulation suggests that small JYW polychrome rimswill almost always be mistyped as bichromes.

COMPENSATING FOR NON-DIAGNOSTIC SHERDS

Designing a method to compensate for non-diagnostic sherds in archaeologicalcollections is more complicated than it might first appear. The approach pre-sented here is intended to be illustrative rather than universally applicable,and takes advantage of a particular strength of Jeddito Yellow Ware, namely

FIGURE 3. Grid format for generating simulated sherd data.


the large photographic database of whole vessels housed in the Yellow WareOnline Database.

A straightforward means of compensating for undercounted Sikyatki Poly-chrome sherds involves reapportioning a number of mistyped bichrome andunpainted sherds “back” to the correct Sikyatki Polychrome type. Since the simu-lated sherd data indicate that only 31.9 percent of the sherds from a givenSikyatki Polychrome bowl will be correctly typed as Sikyatki Polychrome, wemay infer that for every one observed Sikyatki Polychrome sherd there are anadditional 3.2 Sikyatki Polychrome sherds which have been mistyped as eitherbichromes or unpainted. Using the simulated sherd data to estimate the pro-portions of Sikyatki Polychrome sherds misclassified into bichrome (46.2percent) and unpainted (21.9 percent), it is possible to calculate the numberof sherds in these categories to reapportion to Sikyatki Polychrome. Anexample of Hypothetical Site A follows (Figure 4):

1. Given a site with 500 unpainted sherds, 1,000 bichrome sherds, and 50Sikyatki Polychrome sherds,

TABLE 7. Simulated Sherds from Whole Pots, Presence of Paint Colors by Type.

TypeUnpaintedN (%)

Black onlyN (%)

Red onlyN (%)

Black and redN (%)

TotalN

Bichrome Early 9 (1.5) 619 (98.6) 0 0 628

BichromeMiddle

151 (7.9) 1762 (92.1) 0 0 1913

Bichrome Late 100 (32.4) 209 (67.6) 0 0 309

Bichrome All 260 (9) 2590 (90.9) 0 0 2850

Sikyatki PolyMiddle

208 (21.2) 417 (42.6) 18 (1.8) 336 (34.3) 979

Sikyatki PolyLate

157 (23.0) 350 (51.3) 10 (1.5) 165 (24.2) 682

Sikyatki All 365 (21.9) 767 (46.2) 28 (1.7) 501 (30.2) 1661

TABLE 8. Percentage of Polychromes Mistyped as Bichromes, Simulated Data.

Sikyatki Polychrome style Percentage of Polychromes Mistyped as Bichromes

Middle Style 42.6

Late Style 46.2


2. Multiply the observed Sikyatki Polychrome sherds * 3.2 = 1603. Reapportion 46.2 percent of 160 (= 74) sherds from bichrome to Sikyatki

Polychrome4. Reapportion 21.9 percent of 160 (= 35) sherds from unpainted to Sikyatki

Polychrome5. New assemblage frequencies: 465 unpainted, 926 bichrome, 160 Sikyatki

Polychrome

To evaluate the effect of undercounting polychromes on site occupationspans, the hypothetical sherd assemblage was analyzed using Kintigh’s (2004)ARRANGE program. The method used by the program is described in Steponai-tis and Kintigh (1993). Briefly, the program distributes the number of sherds inan assemblage over the types’ ranges of production, creating a “compositeceramic distribution”—a “kind of probability distribution, the area under thecurve suggesting the likelihood that the site was occupied over any given intervalof time” (Kintigh 2004:71). Starting and ending dates are estimated from the12.5th and 87.5th percentiles, which bracket 75 percent of the area of the curve.5

FIGURE 4. Uncorrected and corrected sherd counts, Hypothetical Site A.


When the number of polychromes in an assemblage is relatively small, asin Hypothetical Site A, the effect of undercounting Sikyatki Polychromes is rela-tively modest. Comparing the uncorrected assemblage from Hypothetical Site Aof 1,000 bichrome sherds and 50 polychrome sherds to the corrected assemblageof 928 bichrome and 155 polychrome sherds produces mean dates that differ byonly nine years (A.D. 1405 vs. A.D. 1414) and composite ceramic distributioncurves that differ only modestly (A.D. 1350–1472 vs. A.D. 1352–1491; Figure 5).

When the observed frequency of Sikyatki Polychrome is higher, however,the distorting effects of undercounting on site occupation estimates increase. Forexample, for Hypothetical Site B (Figure 6):

1. Given a site with 500 unpainted sherds, 1,000 bichrome sherds, and 500Sikyatki Polychrome sherds,

2. Multiple the observed Polychrome sherds * 3.2 = 1600

FIGURE 5. Composite ceramic distribution plot, Hypothetical Site A. The dashed lines mark the12.5 and 87.5th percentiles.


3. Reapportion 46.2 percent of 1,600 (= 739) sherds from bichrome to SikyatkiPolychrome

4. Reapportion 21.9 percent of 1,600 (= 347) sherds from unpainted to SikyatkiPolychrome

5. New assemblage frequencies: 153 unpainted, 261 bichrome, 1600 SikyatkiPolychrome.

In this case, the mean ceramic dates differ by 52 years (A.D. 1433 vs. 1485)and the composite ceramic distribution curves differ significantly, with theobserved frequencies suggesting an occupation range from A.D. 1357–1521and the adjusted frequencies suggesting a range from 1412–1561 (Figure 7).

At the most extreme, if the number of observed unpainted sherds plus thenumber of bichrome sherds is less than 3.2 * the number of Sikyatki Polychromesherds, then it may be inferred that virtually the entire decorated sherd assem-blage derives from polychrome vessels. More specifically, if

B , 0:462�ð3:2�SÞ

FIGURE 6. Uncorrected and corrected sherd counts, Hypothetical Site B.


(where B = the number of bichrome sherds and S = the number of Sikyatki Poly-chrome sherds) then it may be inferred that virtually the entire decorated sherdassemblage derives from polychrome vessels.

INTERPRETING THE ABSENCE OF SIKYATKI POLYCHROME SHERDS

More difficult to correct are situations in which no Sikyatki Polychromes areobserved in the sherd assemblage, but some might be expected. In this situation,how do we decide whether the absence of Sikyatki Polychrome is due to the factthat the site predates polychrome manufacture, or to social dynamics affectingthe distribution of Sikyatki Polychrome, or to the non-diagnostic sherdproblem? Here, a binomial approach provides a basis for evaluating sherdfrequencies.

This particular problem applies primarily to sites occupied in the mid- tolate fourteenth century, when Sikyatki Polychrome was just beginning to be pro-duced, and when polychromes comprised a relatively small proportion of total

FIGURE 7. Composite ceramic distribution plot, Hypothetical Site B. The dashed lines mark the12.5 and 87.5th percentiles.


decorated Jeddito Yellow Ware. To evaluate a situation in which a mid- to latefourteenth-century Jeddito Yellow Ware assemblage produced no Sikyatki Poly-chrome, sherd counts from Homol’ovi II (occupied ca. A.D. 1350–1400) wereused to estimate the “true” probability (p) of finding a Sikyatki Polychromesherd (.009, the proportion of Sikyatki Polychrome sherds at Homol’ovi II)(see Table 2). This “probability of success” was then used to calculate binomialprobabilities of drawing zero Sikyatki Polychrome sherds and one or moreSikyatki Polychrome sherds in samples of 10 to 500 sherds from a hypotheticalmid- to late fourteenth-century site (Table 9).

TABLE 9. Probability (P) of drawing zero or one or more Sikyatki Polychrome sherds given aprobability of success (p) of .009 (observed proportion of Sikyatki Polychrome sherds atHomol’ovi II; see Table 3).

Sample Size P (≥1) P (0)

10 0.09 0.91

25 0.20 0.80

50 0.36 0.64

75 0.49 0.51

100 0.60 0.40

125 0.68 0.32

150 0.74 0.26

175 0.79 0.21

200 0.84 0.16

225 0.87 0.13

250 0.89 0.11

275 0.92 0.08

300 0.93 0.07

325 0.95 0.05

350 0.96 0.04

375 0.97 0.03

400 0.97 0.03

425 0.98 0.02

450 0.98 0.02

475 0.99 0.01

500 0.99 0.01


Table 9 reveals that relatively large sample sizes of Jeddito Yellow Ware arerequired to have confidence that the absence of Sikyatki Polychrome is notsimply due to sampling error (n = 275 to reach a probability of success of.90). Since relatively few sites have systematic JYW collections greater than275 sherds (especially those that have not been excavated), this result suggeststhat the absence of Sikyatki Polychrome sherds is often “overinterpreted.”That is, we are too readily accepting the absence of Sikyatki Polychrome in asherd assemblage as an indication that the site’s occupation terminated beforeA.D. 1385, when in fact our sample does not warrant making that conclusion.As a result, we may often be underestimating the end of many late fourteenth-century site occupations with Hopi ceramics. We may also be over-interpretingthe absence of Sikyatki Polychrome from a social perspective as it relates tostatus, trade, migration, etc.

Given these results, when recording fourteenth-century sites where JedditoYellow Ware is present it may be advisable to supplement randomly placedceramic collection units with a sweep of the site’s surface to locate Sikyatki Poly-chromes. While such sherds cannot be counted as part of a representative sampleor included in mean ceramic date calculations, their presence may be useful injudgmentally adjusting “end of occupation” estimates or in making inferencesabout social dynamics from the presence/absence of polychromes.

CASE STUDY

To explore the chronological and social implications of the non-diagnostic sherdproblem with a “real world” example, the compensation formula can be appliedto villages from the Anderson Mesa region. Pueblo IV period Anderson Mesaoccupation is concentrated into two settlement clusters, one at Chavez Pass con-sisting of three nearby pueblos (Chavez North, Chavez Southwest and ChavezSoutheast) and a more dispersed cluster 8 miles to the northwest (Pollock, Kin-nikinnick, and Grapevine) (Bernardini and Brown 2004) (Figure 2). Archaeolo-gists have long recognized the gap at Chavez Pass as a natural trade routebetween the Colorado Plateau and the Verde Valley, and the archaeology ofAnderson Mesa Pueblo IV sites reflects the role of these villages as a centralnode in an interaction sphere that covered much of northern and centralArizona. The ceramic assemblages of Pueblo IV Anderson Mesa villages arediverse, even though none of the decorated ceramics were probably producedon site. Jeddito Yellow Ware is notably abundant at Anderson Mesa sites(Benitez 1998), potentially signaling strong relationships with contempora-neous Hopi villages that became destination points for many migrants overthe fourteenth century (Bernardini 2005).

To what extent has the non-diagnostic sherd problem affected chronologi-cal and social interpretations of Jeddito Yellow Ware at Anderson Mesa villages?


Raw Jeddito Yellow Ware counts by village are presented in Table 10. JedditoYellow Ware is present at all villages except Pollock (which has a small surfacecollection); only two pieces were recovered from Chavez North. Only a singlesherd of Sikyatki Polychrome was recovered from Anderson Mesa, at ChavezSE. With respect to chronology, the absence of Sikyatki Polychrome at all butone Anderson Mesa site (and its rarity there) has been used to argue that occu-pation in the region likely ended before A.D. 1385 (Bernardini and Brown2004). The adjustments of type frequencies produced by the compensationformula in this case are modest, raising the number of Sikyatki Polychromesherds at Chavez SE from one to three. While this might strengthen the inferencethat this site did persist until at least 1385, it does not radically change its dating.

Using binomial probabilities to help interpret the absence of SikyatkiPolychrome suggests more significant revisions in interpretation. In Table 10,the values in the “polychrome probability” row represent the probability of dis-covering one or more polychrome sherds given the observed Jeddito YellowWare sample size. In other words, values represent the level of confidence wecan have that the absence of Sikyatki Polychrome is due to the behavior of thesite’s occupants (e.g., leaving the site before A.D. 1385, or failing to acquireSikyatki Polychrome ceramics available in circulation), as opposed to samplingerror. Table 10 shows that only at Chavez SW is the sample of JYW large enoughto justify more than 75 percent confidence that the absence of Sikyatki Poly-chrome actually reflects the behavior of the site’s occupants. Jeddito YellowWare sample sizes at the other sites are probably too small to confidentlyexplain the absence of Sikyatki Polychrome as a result of behavior rather thanchance. In light of these probabilities, the conclusion by Upham et al. (1981)that the most “labor intensive” ceramics (polychromes) were concentrated atChavez SW and Chavez SE as result of the higher social status of their occupantsof residents relative to those in the northern settlement cluster may therefore beunwarranted, or at least only weakly supported (see also Adams et al. 1993).

TABLE 10. Anderson Mesa Ceramic Data.

ChavezN

ChavezSW

ChavezSE Grapevine Pollock Kinnikinnick Total

Bichrome 4 167 89 54 0 73 387

Polychrome 0 0 1 0 0 0 1

Polychromeprobability1

0.04 0.78 0.55 0.39 – 0.48 0.97

Total 4 167 90 54 0 73 388

1 The probability of drawing one or more polychrome sherds given the observed JYW sample size.


CONCLUSIONS

The non-diagnostic sherd problem is likely to be present in any sherd assem-blage featuring RAT ceramics whose diagnostic attributes cover only a smallportion of the vessel. This problem is likely to plague many polychrome typesin particular due to the typically sparse use of secondary paint colors. The non-diagnostic sherd problem affects assemblages in which RAT vessels existed inlow frequencies to begin with by reducing the chance of recovering a diagnosticpiece of these vessels. The problem also affects assemblages with large amountsof RAT vessels, because the volume of non-diagnostic sherds produced frombroken RAT pots can swamp the diagnostic sherds, distorting chronological esti-mates or measures of social dynamics (e.g., trade, migration, status, etc.).

The research reported here should be treated as only a preliminary explora-tion of the non-diagnostic sherd problem. More realistic sherd simulation datamight be generated from a study of crushed but reconstructed whole vessels, forexample. More sophisticated compensation formulas might also be producedusing Bayesian logic to incorporate analysts’ prior knowledge about the likelyoccupation span of a site into probability estimates of the presence or frequencyof RATs.

It is hoped that the tentative solutions presented here inspire otherresearchers to explore additional means of compensating for sherd/wholevessel typological issues. Given the centrality of ceramic data to archaeologicalanalyses of chronology and social dynamics, the benefits of correcting for thenon-diagnostic sherd problem are clear.

Notes

1. Temper density in Jeddito Yellow Ware was first studied by Smith (1971:478–480), and while he did find that heavily-tempered pieces are most common inthe early fourteenth-century assemblages (Awatovi Black-on-yellow) and temper-less pieces are typical of assemblages from the late fourteenth century and after(Jeddito Black-on-yellow and Sikyatki Polychrome), there is significant overlapin temper density in the transitional period. Up to 1/3 of the ostensibly temperlessJeddito Black-on-yellow and Sikyatki Polychrome vessels exhibited heavy temperdensities typical of Awatovi Black-on-yellow, while 1/4 of the typically heavilytempered Awatovi Black-on-yellow vessels exhibited light temper densitiesexpected of Jeddito Black-on-yellow and Sikyatki Polychrome. LaMotta (2006)confirmed the general temper trend in a study of Jeddito Yellow Ware fromHomol’ovi I and Homol’ovi II, but made use of the pattern only at the level ofthe assemblage, not for the purposes of typing individual sherds. Thus, whilethere is clearly a directional continuum of temper density over the fourteenthcentury, the fuzziness of the pattern makes temper a relatively unreliable


marker for typing individual sherds.Likewise, Smith’s (1971:476–477) study of Jeddito YellowWare paste color docu-mented a general trend of darker earlier colors (in the Munsell range 7.5YR to10YR) and lighter later colors (1oYR to 2.5YR), but significant variability: 30percent of Awatovi Black-on-yellow vessels were “white”, while 25 percent ofJeddito Black-on-yellow vessels were reddish brown.There remains debate among Jeddito Yellow Ware ceramic specialists aboutwhether the variability around temper and paste color trends is sufficient toexclude them from a sherd typology or whether, in combination with other time-sensitive attributes, they can be used profitably.

2. Paayu Polychrome, which contains thinned shades of black or brown in massedareas to create the effect of a polychrome, dates from 1365 to 1385 in deposits atHomol’ovi I and II and is a clear predecessor to Sikyatki Polychrome. This type hasonly recently been recognized (Hays 1991) and was not distinguished in any ofthe analyses used here.

3. An Early Sikyatki Polychrome variant (ca. A.D. 1385–1400) is also recognized,featuring geometric designs in which red paint is used to outline black solidareas, but this variant is very rare and is not considered in this study.

4. The American Museum of Natural History, the Arizona State Museum, the FieldMuseum, the Brooklyn Museum of Art, the Denver Museum of Natural History,the Logan Museum, the Heard Museum, the Maxwell Museum, the SouthwestMuseum, the Museum of Northern Arizona, the Peabody Museum, the Smithso-nian Museum, the Phoenix Museum of Natural History, the University of Color-ado Museum, the Museum of New Mexico, Montezuma Castle NationalMonument, the University of Pennsylvania Museum of Archaeology andAnthropology.

5. Type production spans were assumed to follow a Gaussian distribution with analpha parameter of 2. Bichrome production dates were set to: introduced A.D.1300, middle of production A.D. 1400, terminated A.D. 1500. Sikyatki Poly-chrome production dates were set to: introduced A.D. 1385, middle of productionA.D. 1500, terminated A.D. 1630.

ACKNOWLEDGEMENTS

I am grateful to Steven LeBlanc, Bob Edberg, and Kelley Hays-Gilpin for theirinvaluable assistance with the Yellow Ware Online Database. Helpful com-ments on drafts of this paper were provided by Linda Cordell, Charles Adams,Kelley Hays-Gilpin, and an anonymous reviewer. I also thank the participantsof the 2009 Yellow Ware Ceramic Conference at the Museum of NorthernArizona and the Amerind Seminar on Jeddito Yellow Ware in 2008 forsharing their knowledge of JYW typology.


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Wesley BernardiniDepartment of Sociology and Anthropology

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The Non-Diagnostic Sherd Problem: Lessons from Jeddito Yellow Ware Typology

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