Biomedical subjects

R Pinchin

Publications and source records attributed to R Pinchin.

18 recordsLinked to original sources

PubMed1998

Interpreting simple STR mixtures using allele peak areas.

Although existing statistical models can interpret mixtures qualitatively based upon the alleles present, the use of automated sequencers opens the opportunity to take account of quantitative aspects embodied by the peak area. One step in understanding simple mixtures consisting of just two donors is to estimate the mixture ratio. This is relatively easy to do when four-allele mixtures are evident at a given locus. However, if the mixture consists of three or fewer alleles, the process it is not straightforward. We demonstrate that mixture estimates are consistent across all loci in a multiplex system. Once the mixture ratio is known, then the expected peak areas for any given combination of alleles can be estimated using a simple spreadsheet analysis.

Alleles↗

PubMed1993

An illustration of the advantages of efficient statistical methods for RFLP analysis in forensic science.

The debate about the statistics of DNA profiling in forensic science casework has been carried out mainly from the perspective which is generally known as "match/binning." This approach has an initial appeal because of its apparent conceptual simplicity. However, the simplicity is illusory because it encourages misconceptions which obscure the essential forensic issues. This is exemplified in a recent report of the National Research Council, which places great emphasis on the need for conservative estimation of relative frequencies while missing the point that the power of RFLP technology cannot be realized if the matching stage is inefficient. Our approach to the problem is a one-stage rather than a two-stage process, by means of one function--the likelihood ratio--which determines the evidential strength. This paper describes experiments which have been carried out to assess the power of the method in forensic science and compares it with match/binning methodology. Tests for gauging the effects of between-probe dependence are included, with the results complementing those of Risch and Devlin.

Biometry↗

PubMed1992

Efficient retrieval from DNA databases: based on the second European DNA Profiling Group collaborative experiment.

We describe an experiment to investigate the potential effectiveness of an international DNA database for linking unsolved crimes using the data from a collaborative exercise among members of the European DNA Profiling Group. We show that effective retrieval of unknown samples will be feasible even from large databases provided that the conditions that were adopted for the collaborative exercise are maintained.

Bayes Theorem↗

PubMed1991

DNA single locus profiles: tests for the robustness of statistical procedures within the context of forensic science.

We describe a series of experiments, carried out on data from DNA profiles, which have been designed specifically to test the validity of the statistical procedures currently used in the Home Office Forensic Science Service. The tests address issues which have been the subject of topical debate, in particular those of representativeness and band independence. The results confirm the confidence which had already been placed in the established procedures. We recommend that all practitioners in the forensic field should carry out similar testing on their own data collections.

DNA Fingerprinting↗

PubMed1981

Comparison of techniques for detection of domestic infestations with Triatoma infestans in Brazil.

The detection of infestations of Triatominae in houses in regions endemic for Chagas's disease is a criterion frequently used in the selection of areas, or of individual houses, for treatment in insecticide campaigns as well as in the evaluation of insecticide performance. Several different methods for detecting domestic infestations with Triatominae were compared: night capture, capture of five bugs with the aid of a flushing-out agent and use of card boxes of the Gómez-Núñez type. The flushing-out and Gómez-Núñez box methods were found to be equally sensitive, although each failed to detect some infestations which the other detected. The night capture method was slightly more sensitive but was found to be impractical for insecticide trials. Improvement to the flushing-out method, notably the introduction of a systematic search technique, made it much more sensitive than the Gómez-Núñez box method for heavily infested houses and for houses three months after insecticide treatment. Although the sensitivity of the Gómez-Núñez box method increases when the boxes are left in place for a long time, this also limits the value of the information obtained regarding the evaluation of insecticides. On the basis of the results presented, the flushing-out method using a systematic search of the house was found to be the most suitable sampling technique, but it is recognized that this method still has limitations.

Animals↗

PubMed1981