Browsing by Autor "Matthew Williams"

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‘Lock them up and throw away the key’: an evaluation of the structure of punitive attitudes
(Taylor & Francis, 2024) Nicolás Trajtenberg; Pablo Ezquerra; Matthew Williams
Criminologists have developed different measures of public attitudes toward punishment. However, most of the research focuses on the explanation of punitive attitudes with scarce evaluation of the structure of the concept. The goal of this article is to conduct a sounder assessment of the measurement properties of punitive attitudes using exploratory and confirmatory analysis including bifactor analysis in a representative sample of 895 individuals. Results suggest that although confirmatory factor analysis shows that punitive attitudes are multidimensional, bifactor analysis provides support for a more unidimensional characterisation of the scale. Results suggest that conclusions regarding the dimensionality of punitive attitudes should be tempered by the type of analysis that is conducted. We finish discussing the implications for future research.
Optimised in-solution enrichment of over a million ancient human SNPs
(2024) Roberta Davidson; Xavier Roca‐Rada; Shyamsundar Ravishankar; Leonard Taufik; Christian Haarkötter; Evelyn Collen; Matthew Williams; Peter Webb; Muket Mahmud; Erlin Novita Idje Djami
Abstract In-solution hybridisation enrichment of genetic markers is a method of choice in paleogenomic studies, where the DNA of interest is generally heavily fragmented and contaminated with environmental DNA, and where the retrieval of genetic data comparable between individuals is challenging. Here, we benchmarked the commercial “Twist Ancient DNA” reagent from Twist Biosciences using sequencing libraries from ancestrally diverse ancient human samples with low to high endogenous DNA content (0.1–44%). For each library, we tested one and two rounds of enrichment, and assessed performance compared to deep shotgun sequencing. We find that the “Twist Ancient DNA” assay provides robust enrichment of ∼1.2M target SNPs without introducing allelic bias that may interfere with downstream population genetics analyses. Additionally, we show that pooling up to 4 sequencing libraries and performing two rounds of enrichment is both reliable and cost-effective for libraries with less than 27% endogenous DNA content. Above 38% endogenous content, a maximum of one round of enrichment is recommended for cost-effectiveness and to preserve library complexity. In conclusion, we provide researchers in the field of human paleogenomics with a comprehensive understanding of the strengths and limitations of different sequencing and enrichment strategies, and our results offer practical guidance for optimising experimental protocols.