The issue of privies in New Orleans being used to extrapolate is not unusual. Unfortunately, the archaeological literature provides far too many examples of the violation of a formal fallacy in logic, the fallacy of extrapolation. In this error, the researcher takes data from a single site and uses it make generalizing comments about a community or even an entire culture. Archaeologists do this all the time and it is wrong!
To take a single feature from a site, be it privy, trash pit, cellar, or whatever and use it to extrapolate very far is foolishness indeed. The limit of valid extrapolation should not, in most cases, go beyond that particular site. Indeed, one can find many cases where a deposition--like in a privy--captures such short time period relative to the entire siteıs occupation dates, that it is merely a snapshot in time. Think of these deposits as being a photograph. How many photographs of a familyıs life present a valid picture of their history and the full richness of their lives? Historical sites are occupied for generations, usually, so how many more photographs would be needed?
For some 25 years now I have advocated taking a community approach to historical archaeology, in which many different sites, representing the diversity of the community, are investigated. In our study of Silcott, Washington, I examined this issue of valid sampling and the need for what later was called ³Middle Range Theory² (Adams 1977). I wanted to do an historical ethnography of that early 20th century community and recognized that the only valid way to approach this was to sample different kinds of sites, as well as extensive interviews and archival research. We excavated a general store, residences, work buildings, and dumps. The general storeıs trash dump contained thousands of artifacts. By artifact I mean objects, not those meaningless fragment counts some researchers use. Despite the huge sample size and variation, and even with excellent preservation (e.g., stamps, egg shells), was this dump representative of the entire range of merchandise available at this store? NO! Was it fully representative of the community? NO. But it was probably as close as we will ever get to that ideal.
Hence, I have little patience with researchers who try characterizing an entire site (much less a neighborhood, community, or culture) based upon using small samples from just a few areas on a site. We CANNOT make important statements on much of anything without paying close attention to the problem of sample size, sample variation, and addressing the formal fallacy of extrapolation.
In one study in Boston, a researcher sampled five sites, seemingly a good start. Between 4 and 6 test units were placed on each site, but the total area sampled was less than what would equate to be a 2x2 meter test unit (Spencer-Wood 1987a). How can such a minuscule sample be used to do anything! It certainly cannot be used to provide a valid study of consumer choice, as it reported to be.
If one wants other examples of how people have tried to do something with nothing, just turn to some of the other chapters in the same book edited by Spencer-Wood (1987b). I have fully reviewed the book elsewhere (Adams 1990). The authors of many of these chapters extrapolate about a site based on a single feature and go on to make grand statements of socioeconomic decline or some other ridiculous assertion which their data are woefully inadequate to address. One site is characterized on the basis of 12 fish. A tavern is characterized by a sample of 18 fish (MNI). Reduction absurd. How many fish are eaten in a single day in a busy tavern? Does anyone really think such a sample can possibly be valid?
Adams, William Hampton
1977 Silcott, Washington: ethnoarchaeology of a rural American community. Reports of Investigations 54. Laboratory of Anthropology, Washington State University, Pullman.
1990 Review of: Consumer choice in historical archaeology, edited by Suzanne M. Spencer-Wood. Historical Archaeology 24(3):118-21.
Spencer-Wood, Suzanne
1987a Millerıs Indices and Consumer Choice Profiles: Status-Related Behaviors and White Ceramics, Consumer Choice and Socio-Economic Status in Historical Archaeology, edited by Suzanne Spencer-Wood, pp. 321-58. Plenum Press, New York, NY.
1987b Consumer Choice and Socio-Economic Status in Historical Archaeology. Plenum Press, New York, NY.
Bill Adams
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