Mixture Analysis and its Preliminary Application in Archaeology

Dong, Zhuan

doi:10.1006/jasc.1996.0100

Cited by 34 publications

(42 citation statements)

References 70 publications

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“…According to the calculated cut-off point y Ã , the method gives, for each measurement, an estimation of the proportion of males and females in the samples, as well as the value of the misclassification error e. The misclassification error e is the sum of the probability of classifying all y greater than y Ã in group 1 knowing that they belong to group 2, plus the probability of classifying all y smaller than y Ã in group 2 knowing that they belong to group 1. For more details on the mathematical model and on various applications of mixture analysis, readers are referred to Aitkin & Wilson, 1980;Everitt, 1984;Flury et al, 1992;Airoldi et al, 1995;Dong, 1997;Monchot, 1999Monchot, , 2000Monchot & Lechelle, 2002. …”

Section: Mixture Analysismentioning

confidence: 99%

“…Traditionally, sexual dimorphism reflected in the size of long bones has been described by the use of bivariate scattergrams of measurements or univariate frequency distributions of metric indices (Altuna, 1978;Cuggiani, 1981;, 1991Herrera, 1988;David & Enloe, 1993;Weinstock, 2000;Fernández, 2001;Zeder, 2001). These methods have various limitations (arbitrary boundary between the estimated groups, real assessment of the width of the histogram; see Dong, 1997;Monchot & Lechelle, 2002) that make it difficult to assign specimens to one or the other sex, especially when there is some overlap between the groups.…”

Section: Introductionmentioning

confidence: 99%

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Sexual dimorphism in limb bones of ibex (Capra ibex L.): mixture analysis applied to modern and fossil data

Fernández

Monchot²

2006

Intl J of Osteoarchaeology

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Estimating sex ratios of fossil bone assemblages is an important step in the determination of demographic profiles, which are essential for understanding the palaeobiology and palaeoethology of any particular species, as well as its exploitation patterns by humans. This is especially true for ibex (Capra ibex), which was a main source of food for hominids during Pleistocene times. Classical methods for determining sexual dimorphism and sex ratio, such as analyses using uni-and bivariate plots, are based on an arbitrary fixing of limits between sexes. Here we use a more robust statistical method termed mixture analysis (MA) to determine the sex of postcranial remains (long bones, metapodials and tarsals) from ibex. For the first time, we apply MA to both a modern and a fossil sample of one species, by using metric data taken from (i) a collection of present-day ibex skeletons and (ii) a Palaeolithic sample of the same species. Our results clearly show that the forelimb (humerus and radius) is more dimorphic than the hindlimb (femur and tibia) and is therefore better suited for sexing ibex. It also appears that metapodials should be used carefully for estimating sex ratios. On the basis of these results, we propose a classification of bone measurements that are more or less reliable for sexing ibex. The results of MA applied to the ibex fossil bones from the Upper Palaeolithic site of the Observatoire (Monaco) lead us to the conclusion that this assemblage consists of a majority of males. The quantitative estimations calculated by the MA make it possible to compare the size of Pleistocene and modern ibex for the whole set of variables used in this study.

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Section: Mixture Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism in limb bones of ibex (Capra ibex L.): mixture analysis applied to modern and fossil data

Fernández

Monchot²

2006

Intl J of Osteoarchaeology

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“…Josephson et al (1996) describe the exact process for estimating dimorphism by the method of moments. This technique is a form of finite mixture analysis (Dong, 1997;Godfrey et al, 1993;Kramer and Konigsberg, 1999). Briefly, the method of moments technique estimates the theoretical underlying male and female distributions from a combined male-female (pooled) sample based on observations in that sample.…”

Section: Estimators Of Dimorphismmentioning

confidence: 99%

Estimating sexual dimorphism and size differences in the fossil record: A test of methods

Rehg

Leigh

1999

Am. J. Phys. Anthropol.

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Investigations of size variation in fossil and archaeological skeletal assemblages may be complicated by incomplete skeletons, biased representation of sexes, and the lack of morphological features that identify sex. In order to refine our ability to evaluate size variation, we test the accuracy of three methods that are currently used to estimate size differences in unsexed (pooled) samples: the means method, the median method, and a newly applied technique, the method of moments. Using body mass data from 42 primate species, we calculated actual levels of sexual dimorphism for each species and compared these values to estimates produced by each method. Multivariate regression was used to examine the effects of sample distribution characteristics, including sample size, kurtosis, skewness, sample variance, sex ratio, and intrasexual variance on the performance of the methods. None of the methods appears to be especially accurate. However, one of the simplest methods, the means method, performs relatively well. Factors that lead to inaccuracies in estimation are not readily evident based on multiple regression analysis. We urge caution in the utilization of these techniques, and advocate further analysis of simulated data. Am J Phys Anthropol 110: 95-104, 1999.

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“…The calculation of sex ratios in fossil remains provides information related to the biology and behavior of animal populations, and in the same way can help to decipher the agents that are responsible for the collection of fossil bone assemblages (Speth, 1983;Davis, 1987). The assessment of sex ratios is also important when trying to analyse evolutionary trends and population dynamics [see Dong (1997)]. Klein and Cruze-Uribe (1983) have suggested, for example, that body size estimates are affected by the sex ratio of the sample being studied.…”

Section: Introductionmentioning

confidence: 99%

A Measure of Sexual Dimorphism in Populations which are Univariate Normal Mixtures

Ipiña

Durand

2000

Bulletin of Mathematical Biology

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Measures of sexual dimorphism have been used extensively to predict the social organization and ecology of animal and human populations. There is, however, no universally accepted measure of phenotypic differences between the sexes. Most indices of sexual dimorphism fail to incorporate all of the information contained in a random data set. In an attempt to have a better alternative, an index is proposed to measure sexual dimorphism in populations that are distributed according to a probabilistic mixture model with two normal components. The index calculates the overlap between two functions that represent the contribution of each sex in the mixture. In order to assess such an index, sample means, variances and sizes of each sex are needed. As a consequence, the sample information used is greater than that used by other indices that take intrasexual variability into account. By evaluating some examples, our proposed index appears to be a more realistic measure of sexual dimorphism than other measures currently used.

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Mixture Analysis and its Preliminary Application in Archaeology

Cited by 34 publications

References 70 publications

Sexual dimorphism in limb bones of ibex (Capra ibex L.): mixture analysis applied to modern and fossil data

Sexual dimorphism in limb bones of ibex (Capra ibex L.): mixture analysis applied to modern and fossil data

Estimating sexual dimorphism and size differences in the fossil record: A test of methods

A Measure of Sexual Dimorphism in Populations which are Univariate Normal Mixtures

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