Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context
In cases where multiple questioned individuals are separately supported as contributors to a mixed DNA profile, guidance documents recommend performing a comparison to see if there is support for their joint contribution. Anecdotal observations suggest the summed log of the individual likelihood rat...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-11-01
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| Series: | Genes |
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| Online Access: | https://www.mdpi.com/2073-4425/13/11/2031 |
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| author | Kyle Duke Daniela Cuenca Steven Myers Jeanette Wallin |
| author_facet | Kyle Duke Daniela Cuenca Steven Myers Jeanette Wallin |
| author_sort | Kyle Duke |
| collection | DOAJ |
| description | In cases where multiple questioned individuals are separately supported as contributors to a mixed DNA profile, guidance documents recommend performing a comparison to see if there is support for their joint contribution. Anecdotal observations suggest the summed log of the individual likelihood ratios (LR), termed the simple LR product, should be roughly equivalent to or less than the log(LR) for the joint likelihood ratio, termed the compound LR. To assist casework analysts in evaluating statistical weights applied to a case at hand, this study assessed how consistently compound LRs conform to an additive behavior when compared to the simple LR product counterparts. Two-, three-, and four-person DNA mixture data, of various mixture proportions and DNA inputs, were interpreted by STRmix<sup>®</sup> version 2.8 Probabilistic Genotyping Software. Relative magnitudes of LR increases were found to be dependent on both template level and mixture composition. The distribution of log(LR) differences between all compound/simple LR comparisons was ~−2.7 to ~28.3. This level of information gain was similar to that for compound LR comparisons, with and without interpretation conditioning (~−3.2 to ~27.7). In both scenarios, the probability density peaked at approximately 0.5, indicating the information gain from constrained genotype combinations has a comparable impact on the outcome of LR calculations whether the restriction is applied before or after interpretation. |
| first_indexed | 2024-03-09T19:03:22Z |
| format | Article |
| id | doaj.art-40b148c1480d43199c8437f0852cbc1b |
| institution | Directory Open Access Journal |
| issn | 2073-4425 |
| language | English |
| last_indexed | 2024-03-09T19:03:22Z |
| publishDate | 2022-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Genes |
| spelling | doaj.art-40b148c1480d43199c8437f0852cbc1b2023-11-24T04:48:41ZengMDPI AGGenes2073-44252022-11-011311203110.3390/genes13112031Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping ContextKyle Duke0Daniela Cuenca1Steven Myers2Jeanette Wallin3California Department of Justice, Richmond, CA 94804, USACalifornia Department of Justice, Richmond, CA 94804, USACalifornia Department of Justice, Richmond, CA 94804, USACalifornia Department of Justice, Richmond, CA 94804, USAIn cases where multiple questioned individuals are separately supported as contributors to a mixed DNA profile, guidance documents recommend performing a comparison to see if there is support for their joint contribution. Anecdotal observations suggest the summed log of the individual likelihood ratios (LR), termed the simple LR product, should be roughly equivalent to or less than the log(LR) for the joint likelihood ratio, termed the compound LR. To assist casework analysts in evaluating statistical weights applied to a case at hand, this study assessed how consistently compound LRs conform to an additive behavior when compared to the simple LR product counterparts. Two-, three-, and four-person DNA mixture data, of various mixture proportions and DNA inputs, were interpreted by STRmix<sup>®</sup> version 2.8 Probabilistic Genotyping Software. Relative magnitudes of LR increases were found to be dependent on both template level and mixture composition. The distribution of log(LR) differences between all compound/simple LR comparisons was ~−2.7 to ~28.3. This level of information gain was similar to that for compound LR comparisons, with and without interpretation conditioning (~−3.2 to ~27.7). In both scenarios, the probability density peaked at approximately 0.5, indicating the information gain from constrained genotype combinations has a comparable impact on the outcome of LR calculations whether the restriction is applied before or after interpretation.https://www.mdpi.com/2073-4425/13/11/2031likelihood ratiosub-source propositionsconditioningcompound LRadditive behavior |
| spellingShingle | Kyle Duke Daniela Cuenca Steven Myers Jeanette Wallin Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context Genes likelihood ratio sub-source propositions conditioning compound LR additive behavior |
| title | Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context |
| title_full | Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context |
| title_fullStr | Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context |
| title_full_unstemmed | Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context |
| title_short | Compound and Conditioned Likelihood Ratio Behavior within a Probabilistic Genotyping Context |
| title_sort | compound and conditioned likelihood ratio behavior within a probabilistic genotyping context |
| topic | likelihood ratio sub-source propositions conditioning compound LR additive behavior |
| url | https://www.mdpi.com/2073-4425/13/11/2031 |
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