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166 SMITHSONIAN CONTRIBUTIONS TO ANTHROPOLOGY
ber of individuals per taxon is consistent within
a sample though differing between sites and not
controlled by sample size. What varies between
the sites is the pattern of skeletal recovery. In the
case of the Near Eastern samples, the distribution
of the different bone types within each site's
subsamples are similar. In the case of the bison
samples reported by B. Gilbert (1969:283), this is
clearly not the case. The Woodland sites have a
relative absence of toe bones compared to the
Middle Missouri and Coalescent sites. The result
is widely different effective numbers of individuals.
The point of these comments is to demonstrate
that the curvilinear relationship produced
empirically by a plot of many MNI/E combinations
does not reflect patterned bias in the way
either estimates a consequences population of
whole animals. It is possible to say that any factor
that (1) increases the number of categories of
element types (a trephic factor like the discovery
of new morphological distinctions); (2) increases
the recovery rate of small bone fragments (a
sullegic factor like reducing screen size); or (3)
changes the skeletal recovery pattern (a cultural
factor like a change in the location of animal
processing activities) will vary the relationship
between MNI and E. Whether either effectively
mirrors the finds population is a separate question.
Another method of estimating taxon frequency
in the finds population has been proposed (Gilbert
and Steinfeld, 1977; Hesse and Perkins, 1974;
Holtzman 1979; Perkins, 1973; Wapnish et al.,
1977). It attempts to overcome one weakness of
the MNI approach by using a greater proportion
of the sample, and one weakness of the E approach
by correcting for the variable number of
elements identifiable in different species. Called
the weighted abundance of elements (WAE) by
Holtzman (1979:80), and relative frequency (rf)
by Perkins (1973), it is calculated by dividing E
by the number of bone elements that are potentially
identifiable in a species skeleton. Two
choices exist in the way the division is done. With
one, E is divided by the number of element types
that are actually present in the sample. This is
roughly equivalent to an average MNI. Each
element type is considered an estimator of relative
species frequency. Taking the average minimizes
the risk associated with a single element estimator
(roughly the comparison between a mean and a
mode as a measure of central tendency). With the
other, E is divided by the potential number of
identifiable element types, whether or not they
are actually represented in the sample. With both
choices it is recommended that element types
with extremely low frequency of recovery be omitted
from both values in the calculation. The first
choice reflects the view that only a portion of an
animal's carcass, in many cases, is likely to be
consistently interred in a cultural deposit (for
instance, only foot bones) and that calculations
using the second method would underestimate
taxon frequency. The second method reflects the
view that, in general, whole carcasses are interred
in cultural deposits, and it is the effects of attrition
that reduce the number of element types recovered.
Since the rf estimator is prone to error
from differential preservation, it is critical that
the divisor be chosen with some consideration of
what the choice implies about preservation.
Holtzman (1979) has compared the performance
of rf/WAE and MNI in a series of computer
simulations. He concluded that "in all simulations
the WAE estimates showed generally
smaller mean squared errors than the MNI estimates,
even under most conditions where the
WAE bias was larger than the MNI bias."
Where the distorting effects of natural or cultural
factors are suspected to be large, it is advantageous
to dispense with trying to estimate the
taxon frequency in the finds or consequences
populations. Procedures of this type have been
described by Binford (1978) and Lyman (1977;
1979). These approaches consider faunal remains
as animal parts rather than as whole animals.
The potential resource value (in terms of meat,
fat, sinew, grease) is estimated for each bone
fragment type and multiplied by the bone element
frequency. The output of this kind of analysis
is a description of the resources represented,
not an estimate of the proportion of each species