Bayesian Analysis of DNA Profiling Data in Forensic Identification Applications

The utilization of DNA evidence in cases of forensic identification has become widespread over the last few years. The strength of this evidence against an individual standing trial is typically presented in court in the form of a likelihood ratio (LR) or its reciprocal (the profile match probability). The value of this LR will vary according to the nature of the genetic relationship between the accused and other possible perpetrators of the crime in the population. This paper develops ideas and methods for analysing data and evaluating LRs when the evidence is based on short tandem repeat profiles, with special emphasis placed on a Bayesian approach. These are then applied in the context of a particular quadruplex profiling system used for routine case-work by the UK Forensic Science Service.     

Measurement biases in user involvement research

Considerable research has been conducted to demonstrate user involvement's effect on information system success. User involvement and system success typically have been measured by asking users for their perceptions of these variables. This paper reports on a field study conducted to investigate the possibility that this approach to measuring study variables tends to overstate the benefits of user involvement. The link of user involvement to user satisfaction is found to be significantly weaker when user involvement is assessed by systems analysts than when it is self reported. Further, this difference is found to be greater for systems with few users than for systems with many users. The findings suggest that common method variance and self-serving bias may have overstated the apparent benefits of user involvement in past research on information systems. Suggestions for future research are presented.     

Mistakes that heterosexual people make when trying to appear non-prejudiced: the view from LGB people

In two studies, lesbians, gay men and bisexuals were queried concerning mistakes that well-meaning heterosexual people have made when interacting with them. In qualitative, open-ended research, we determined that the most common mistakes concerned heterosexuals' pointing out that they know someone who is gay, emphasizing their lack of prejudice, and relying on stereotypes about gays. Following up with a quantitative, close-ended questionnaire, we determined that the mistakes respondents experienced most often involved heterosexuals (a) relying on stereotypes and (b) ignoring gay issues; the most annoying mistakes were heterosexuals (a) using subtle prejudicial language and (b) not owning up to their discomfort with gay issues. We used two theoretical perspectives, shared reality theory and the contact hypothesis, to analyze the quantitative responses. Implications for intergroup relationships between heterosexual people and gay people are discussed.     

Attitudes, subjective experiences, and behaviors in imagined and actual encounters between gay and heterosexual people

Across four studies, we assessed the relationship between participants' attitudes toward gay men and their experiences during either imagined or actual interpersonal encounters with gay men. In the first three studies, participants imagined interactions with gay men and either responded in an open-ended or a closed-ended fashion. In these imagined interactions, participants reported that they expected to have considerable agreement between their attitudes and their subjective experiences during the intergroup encounter. However, during actual interactions, there were no differences between members of different prejudice levels in their responses to the gay confederate. A comparison of the actual and imagined interactions demonstrated that high prejudice people are particularly unlikely to have subjective experiences that match their negative attitudes concerning actual interpersonal encounters.     

Career story: Consultant Forensic Statistician

Ian Evett works for the Forensic Science Service as a consultant statistician. He tells Helen Joyce about the contribution a statistician can make to analysing handwriting, glass, DNA and other forensic materials, as well as to understanding the fundamentals of evidence interpretation.     

Gay men and lesbians' experiences in and expectations for interactions with heterosexuals

We analyzed 97 gay men's and lesbians' experiences with and expectations for interactions with majority group members. Respondents described reactions to previous or imagined future interactions with an unfamiliar heterosexual person who had just become aware that the respondent was lesbian or gay. Results indicated that respondents are more proactive than reactive (in contrast to expectation states theories), that the contact hypothesis can be appropriately applied to this group, even though the formulation of the theory was based upon negative attitudes in the absence of extensive contact, and that they have different reactions for people of different prejudice levels, rather than being globally suspicious, as is predicted by many intergroup theories. Future research should direct more attention to the stigmatized group members' attitudes about and reactions toward the majority group.