Block Randomized Trials at Places: Rethinking the Limitations of Small N Experiments

Objectives

Place-based policing experiments have led to encouraging findings regarding the ability of the police to prevent crime, but sample sizes in many of the key studies in this area are small. Farrington and colleagues argue that experiments with fewer than 50 cases per group are not likely to achieve realistic pre-test balance and have excluded such studies from their influential systematic reviews of experimental research. A related criticism of such studies is that their statistical power under traditional assumptions is also likely to be low. In this paper, we show that block randomization can overcome these design limitations.

Methods

Using data from the Jersey City Drug Market Analysis Experiment (N = 28 per group) we conduct simulations on three key outcome measures. Simulations of simple randomization with 28 and 50 cases per group are compared to simulations of block randomization with 28 cases. We illustrate the statistical modeling benefits of the block randomization approach through examination of sums of squares in GLM models and by estimating minimum detectable effects in a power analysis.

Results

The block randomization simulation is found to produce many fewer significantly unbalanced samples than the naïve randomization approaches both with 28 and 50 cases per group. Block randomization also produced similar or smaller absolute mean differences across the simulations. Illustrations using sums of squares show that error variance in the block randomization model is reduced for each of the three outcomes. Power estimates are comparable or higher using block randomization with 28 cases per group as opposed to naïve randomization with 50 cases per group.

Conclusions

Block randomization provides a solution to the small N problem in place-based experiments that addresses concerns about both equivalence and statistical power. The authors also argue that a 50 case rule should not be applied to block randomized place-based trials for inclusion in key reviews.     

Participation as a Framework for Analysing Consumers’ Experiences of Alternative Dispute Resolution (ADR)

This article argues that an analytic framework based on participation is useful for analysing consumer experiences of alternative dispute resolution (ADR), providing a complementary approach to analyses drawing on procedural justice theory. The argument is developed by applying McKeever's ‘ladder of legal participation’ (LLP)¹ to a qualitative data set consisting of interviews with United Kingdom consumers. The article concludes that applying the LLP in the consumer ADR context results in novel empirical and theoretical insights. Empirically, it demonstrates that – even in low-value and transactional disputes – consumers expect high levels of participation from ADR. Theoretically, it argues that the LLP complements existing approaches by providing an unifying lens through which to study consumer experiences by emphasizing the importance of participation, not only as a process value but also in shaping outcomes highlighting the distinction between genuine and tokenistic provision of ADR.     

Women,love and power in Enlightenment Scotland

The significance of the Enlightenment for women’s power in society and culture has been a topic of significant historiographical debate. This article looks at how women were located within the discourse of the Scottish Enlightenment and its implications for elite women’s role within public and private life in eighteenth-century Scotland. It argues that women were located as helpmeets to men, a designation that authorised their access to education and to some areas of public debate, but that their authority rested on their ability to improve the position of men, rather than enabling them as autonomous agents. To make this argument it draws together case studies of women’s role in the home and family, with their engagement in public life and as authors, demonstrating how similar values shaped their role in each sphere.     

Survivor-Centered Research: Towards an Intersectional Gender-Based Violence Movement

Much has been written on the imperative of intersectionality within the fight for women’s equality and in efforts to end gender-based violence. However, data continues to show that women and LGBTQ people of color experience heightened and more severe instances of both state and interpersonal violence. What lessons can domestic violence and sexual assault advocates and researchers learn from intersectional theory and frameworks to help reduce instances of violence, reduce barriers in accessing resources and create safety nets for communities? This paper seeks to explore the roots of historical violence against communities of color, the current trends in anti-violence research and service provision and strategies for engaging in intersectional community based research.     

Development of a simulation model to assess the impact of contamination in casework using STRs

Because contamination is usually tube-specific, negative controls cannot give assurance that an associated batch of extracted casework material is contaminant-free. However, it is possible to use them to predict the level of overall (undetected) contamination that is processed by an operational DNA unit. A MATLAB-based program was used to combine results of negative controls with actual casework DNA profiles to assess the probability that laboratory contaminants will give rise to reportable profiles (along with their likelihood ratios). Using data from an operational DNA unit as an example, it was demonstrated that the risk is inextricably linked to guidelines used to interpret DNA profiles. We have demonstrated how computer-based models can predict the levels of contamination expected in the process and, in addition, how the process can be made more robust by changing reporting guidelines. There is a need to compare DNA profiles against staff and plasticware elimination databases in order to determine sources of contamination. The likeliest outcome of a contamination event is false exclusion.     

Bodies found in the waterways of New York City

We reviewed the case records for all decedents recovered from the waterways of New York City over a three year period (1997-2000). The epidemiological profile, circumstances, toxicology findings, putrefactive changes, date of recovery, length of immersion, and injuries were examined. There were 123 deaths: 52 suicides, 50 undetermined, 16 accidents, and five homicides. The causes of death included: 97 drownings, 13 undetermined, and 13 other. Of all the floating decedents, 27% were without putrefactive change. All found after two or more weeks of immersion were recovered from November to May. The detection of ethanol and illicit drugs was 53% in the accident, 41% in the suicide, and 33% in the undetermined groups. Detection of ethanol and/or drugs of abuse is not a reliable criterion to distinguish suicide from accident. The identification of the deceased is pivotal for determining the manner of these deaths. Therefore, a great reliance is placed upon the medical investigator and the police (including the missing persons bureau) to determine the circumstances and identification of the decedent.