Validation study of the proposed seventh phase of the Suchey-Brooks age estimation method for the pubic symphysis
Cloven, Jasmine M.
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The Suchey-Brooks (1990) method for estimating adult age-at-death from the pubic symphysis is widely used and popular among forensic anthropologists. While this technique is quite accurate, it yields wide age interval estimates and is imprecise for individuals aged over fifty years at death. Berg (2008) and Hartnett (2010a) each altered Brooks and Suchey's phase descriptions and added a seventh phase with the goal of increasing precision while maintaining accuracy, especially for older individuals. The hypothesis for this validation study states that the new methods improve the existing Suchey-Brooks method. A total of 384 White Americans (n=213 males and 171 females) aged 26-97 years at death were analyzed at the William M. Bass Donated Skeletal Collection at the University of Tennessee, Knoxville using all three methods. Descriptive statistics, percentages of "correct" age estimates, inaccuracy and bias scores, and rates of inter- and intra-observer agreement were calculated and compared across the three methods. The Hartnett and Suchey-Brooks methods yielded similar percentages of correct estimates for males (85.0% and 84.5% correct, respectively, using ±2 standard deviations from the phase means), although the Hartnett method was significantly less inaccurate (p<0.001) and biased (p<0.001). The Suchey-Brooks method yielded the highest percentage of "correct" estimates for females aged less than sixty years (100.0% using ±2 standard deviations or 83.1% using ±1 standard deviation) and was significantly less inaccurate (p<0.001) and biased (p<0.001) than the Hartnett and Berg methods. The Hartnett and Berg methods were both significantly (p<0.001) less inaccurate and biased than the Suchey-Brooks method for females aged over sixty years, but Hartnett's and Berg's scores were not significantly different from each other (p=0.496 inaccuracy, p=0.066 bias). The Berg method yielded the highest percentage of "correct" estimates for females aged greater than sixty years (90.2% using ±2 standard deviations or 54.5% using ±1 standard deviation). The results of the present study were similar to those obtained by Merritt's (2014) validation study of Hartnett (2010a, b), although Merritt's rates of intra-observer agreement were substantially higher than those calculated for the present study. The hypothesis for the present study was supported.