Publications by authors named "Susan R Frankenberg"

6 Publications

  • Page 1 of 1

Multivariate ordinal probit analysis in the skeletal assessment of sex.

Am J Phys Anthropol 2019 06 29;169(2):385-387. Epub 2019 Mar 29.

Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, Illinois.

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http://dx.doi.org/10.1002/ajpa.23832DOI Listing
June 2019

Typicality and Predictive Distributions in Discriminant Function Analysis.

Hum Biol 2018 Jan;90(1):31-44

1 Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.

While discriminant function analysis is an inherently Bayesian method, researchers attempting to estimate ancestry in human skeletal samples often follow discriminant function analysis with the calculation of frequentist-based typicalities for assigning group membership. Such an approach is problematic because it fails to account for admixture and for variation in why individuals may be classified as outliers or nonmembers of particular groups. This article presents an argument and methodology for employing a fully Bayesian approach in discriminant function analysis applied to cases of ancestry estimation. The approach requires adding the calculation, or estimation, of predictive distributions as the final step in ancestry-focused discriminant analyses. The methods for a fully Bayesian multivariate discriminant analysis are illustrated using craniometrics from identified population samples within the Howells published data. The article also presents ways to visualize predictive distributions calculated in more than three dimensions, explains the limitations of typicality measures, and suggests an analytical route for future studies of ancestry and admixture based in discriminant function analysis.
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January 2018

Status of Mandibular Third Molar Development as Evidence in Legal Age Threshold Cases.

J Forensic Sci 2019 May 8;64(3):680-697. Epub 2018 Oct 8.

Institute of Dentistry, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, E1 2AD, U.K.

The completion of the third molar roots has played an important role in ascertaining whether individuals may be at or over a legal threshold of age, often taken as 18 years. This study demonstrates that root apex completion in the third molar is relatively uninformative regarding the threshold of age 18 years in a sample of 1184 males, where mean age-of-attainment of root apex completion for third mandibular molars is about 19.4 years. This paper also considers the legal age threshold problem for cases where the third mandibular molar is not completely formed, and outlines the use of parametric models and Bayes' factors to evaluate dental evidence in statistically appropriate ways. It attempts to resolve confusion over age-within-stage versus age-of-attainment, likelihood ratios versus other diagnostic tests, and prior odds for a case versus the prior density for an age distribution.
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http://dx.doi.org/10.1111/1556-4029.13926DOI Listing
May 2019

Optimal trait scoring for age estimation.

Am J Phys Anthropol 2016 Apr 12;159(4):557-76. Epub 2015 Dec 12.

Centre for Oral Growth and Development, Institute of Dentistry, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, E1 2AD, London, UK.

Objectives: Little attention has been paid to questions about the applicability of parametric models to age estimation data and the related problem of how to adjust trait scoring in light of potential deviations from particular parametric models. This article addresses this deficit.

Methods: A Lagrange multiplier goodness-of-fit test is applied to two datasets to address the question of whether or not attainment ages for stages are log-normally distributed. The first dataset used in this article consists of scores of the Todd ten-phase system for the pubic symphysis obtained from 938 individuals with known ages. The second dataset consists of scores for 15 stages of formation for the second mandibular molar scored in 2,304 individuals of known age.

Results: For the Todd ten-phase system there is a significant departure from log-normally distributed ages of attainment. To obtain an acceptable goodness-of-fit statistic, Todd scores consequently are collapsed into an eight-phase system that maintains scores I through VII as individual scores but combines phases VIII through X into one phase. The 15-stage scoring system for the second mandibular molar has an acceptable fit to the log-normal distribution for ages of attainment.

Conclusions: The results from the analysis of the Todd pubic symphysis scores show that researchers should use goodness-of-fit tests for parametric models before deciding to collapse scores. Further, such goodness-of-fit tests are an essential tool in answering questions concerning the suitability of various parametric models. For the 15-stage scoring of the second mandibular molar, the log-normal model is appropriate for attainment ages.
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http://dx.doi.org/10.1002/ajpa.22914DOI Listing
April 2016

Bayes in biological anthropology.

Am J Phys Anthropol 2013 Dec 4;152 Suppl 57:153-84. Epub 2013 Nov 4.

Department of Anthropology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801.

In this article, we both contend and illustrate that biological anthropologists, particularly in the Americas, often think like Bayesians but act like frequentists when it comes to analyzing a wide variety of data. In other words, while our research goals and perspectives are rooted in probabilistic thinking and rest on prior knowledge, we often proceed to use statistical hypothesis tests and confidence interval methods unrelated (or tenuously related) to the research questions of interest. We advocate for applying Bayesian analyses to a number of different bioanthropological questions, especially since many of the programming and computational challenges to doing so have been overcome in the past two decades. To facilitate such applications, this article explains Bayesian principles and concepts, and provides concrete examples of Bayesian computer simulations and statistics that address questions relevant to biological anthropology, focusing particularly on bioarchaeology and forensic anthropology. It also simultaneously reviews the use of Bayesian methods and inference within the discipline to date. This article is intended to act as primer to Bayesian methods and inference in biological anthropology, explaining the relationships of various methods to likelihoods or probabilities and to classical statistical models. Our contention is not that traditional frequentist statistics should be rejected outright, but that there are many situations where biological anthropology is better served by taking a Bayesian approach. To this end it is hoped that the examples provided in this article will assist researchers in choosing from among the broad array of statistical methods currently available.
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http://dx.doi.org/10.1002/ajpa.22397DOI Listing
December 2013

Deconstructing death in paleodemography.

Am J Phys Anthropol 2002 Apr;117(4):297-309

Department of Anthropology, University of Tennessee, 250 South Stadium Drive, Knoxville, TN 37996-0720, USA.

In 1992 in this Journal (Konigsberg and Frankenberg [1992] Am. J. Phys. Anthropol. 89:235-256), we wrote about the use of maximum likelihood methods for the "estimation of age structure in anthropological demography." More specifically, we presented a particular method (the "iterated age-length key") from the fisheries literature and suggested that the method could be used in human and primate demography and paleodemography as well. In our paper (section titled "Some Future Directions"), we spelled out two broad areas that we expected to see develop over the ensuing years. First, we felt that the use of explicit likelihood methods would open up interest in basic estimation issues, such as the calculation of standard errors for demographic estimates and the formulation of tests for whether samples differed in their demographic structure. Second, we felt that the time was ripe for hazards analyses that would incorporate the uncertainty in estimation that follows from using age "indicators" rather than known ages. While some of these developments have occurred during the last decade, few have been reported in the American Journal of Physical Anthropology. In this paper we resolve some issues from our 1992 paper, and attempt to redress this deficit in the literature by reviewing some recent developments in paleodemography over the past decade.
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http://dx.doi.org/10.1002/ajpa.10039DOI Listing
April 2002