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.     

Paternity Testing Commission of the International Society of Forensic Genetics: recommendations on genetic investigations in paternity cases

The International Society for Forensic Genetics (ISFG) has established a Paternity Testing Commission (PTC) with the purpose of formulating international recommendations concerning genetic investigations in paternity testing. The PTC recommends that paternity testing be performed in accordance with the ISO 17025 standards. The ISO 17025 standards are general standards for testing laboratories and the PTC offers explanations and recommendations concerning selected areas of special importance to paternity testing.     

Thwarted ambitions: the biography of Auvergne Doherty,an aspiring female barrister

ABSTRACT

Auvergne Doherty was the first woman from the Commonwealth to be admitted and called to the Bar of England and Wales.?In the first part of this article, Doherty's family background, education, legal training, and post-Bar experiences are set out. The second part analyses her profile compared with the other women called to the Bar in 1922 and considers why Doherty may not have gone on to practise as a barrister. This article argues that Doherty’s biography is important because it evidences how vital it was to have the necessary financial means and networks to be able to forget a career at the Bar. It was precisely the lack of these factors that impeded Doherty to fulfil her career as a barrister.     

Public confidence in the police: tests of instrumental and expressive models in a developing country city

This paper examines the effect of instrumental and expressive concerns on public confidence in the police in three different residential areas in Sekondi-Takoradi, Ghana’s third largest city. The study was important because of the knowledge vacuum that existed in regard to the empirical validity of the instrumental and expressive theoretical framework within the Ghanaian context. Data for the study was drawn from a baseline survey conducted in three residential areas in the Sekondi-Takoradi metropolis. The findings revealed that instrumental factors played a more significant role in influencing confidence in the police in the Sekondi-Takoradi metropolis compared to expressive factors. More importantly, instrumental factors played a more significant role in influencing confidence in the police at Anaji compared to the other two residential areas used in the study. The paper recommends that there should be more investment in police infrastructure and services to enhance police effectiveness and efficiency. Additionally, the authors also suggest that interventions aimed at improving security at the community level should be guided by periodic safety audits since this will provide a better understanding of the criminogenic problems within these residential settlements.     

False homozygosities at various loci revealed by discrepancies between commercial kits: implications for genetic databases

Routine control of 2055 consecutive genotypes revealed discrepancies between the profiles established with the SGM plus and/or Profiler plus kits on one hand, and the profiles established with the Powerplex16 kit on the other hand. Furthermore, five discrepancies for vWA, three for D8S1179, two for FGA and three for D18S51 loci were found. In 10 cases (loci vWA, FGA, D18S51, D8S1179), the SGM plus and/or Profiler plus profiles showed homozygosity and the Powerplex16 genotype revealed heterozygosities which were confirmed to be true, both by typing with individual primer pairs and DNA sequencing. In four cases (two discrepancies at locus FGA, one at D18S51 and an abnormal paternity pattern for D5S818), the Powerplex16 kit showed apparent homozygosity and the SGM plus and/or Profiler plus kits showed heterozygosity. Mutation analysis could be performed for some of these individuals and evidenced variants, presumably leading to an annealing failure of one primer; the identified mutations are reported. It is suggested that databases should include information about the kits used to determine the profiles while ensuring that the primer sequences are made available.     

Simultaneous determination of thirteen beta-blockers and one metabolite by gradient high-performance liquid chromatography with photodiode-array UV detection

A new rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed for the simultaneous identification and quantification in human plasma of the 13 most commonly prescribed beta-blockers and one active metabolite-atenolol, sotalol, diacetolol, carteolol, nadolol, pindolol, acebutolol, metoprolol, celiprolol, oxprenolol, labetalol, propranolol, tertatolol and betaxolol. It involves liquid-liquid extraction procedures followed by liquid chromatography coupled to photodiode-array UV detection with a fixed wavelength at 220 nm for quantification. Compounds were separated on a 5 microm Hypurity C(18) (ThermoHypersil) analytical column (250 mm x 4.6 mm, i.d.) using a gradient of acetonitrile-phosphate buffer pH 3.8 at a flow rate of 1.0 ml/min. The total analysis time was 26 min per sample. Extraction recoveries were between 74 and 113% for the polar compounds and between 20 and 56% for the most apolar compounds. Calibration lines were linear in the range from 25 to 1000 ng/ml for all compounds excepted carteolol and nadolol (50-1000 ng/ml), all of them with coefficients of determination (r2 values) >/=0.994. Limits of detection (LODs) ranged from 5 to 10 ng/ml. Intra-assay and inter-assay precision and accuracy were studied at two concentration levels (100 and 500 ng/ml). The intra-assay coefficients of variation (CVs) for all compounds were 相似文献   

nature,nurture and nation: Nísia Floresta's engagement in the breast-feeding debate in Brazil and France

This article looks at the way the Brazilian writer and educator Nísia Floresta addresses issues of race and class within her construction of nationhood. This is achieved through a consideration of the specific subject of maternal breast-feeding as discussed by Floresta in two texts, written in Brazil and France, respectively. A comparison of these works reveals a very different engagement with race and class factors in determining women's claim to citizenship. Floresta, in common with early 19th-century European feminism, believed this claim to lie within the domestic sphere, primarily in the role of mother and educator. The article considers how, as a vital aspect of that role, she portrays maternal breast-feeding as both natural and patriotic. It also highlights the extent to which Floresta was influenced by the prevailing concerns of her contemporaries regarding the risks of wet nursing and the threat posed by household slaves, before going on to consider how this discourse leads Floresta to exclude black slave women from her vision of patriotic motherhood, while acknowledging the maternity of women of all classes in a European context. Patriotic concerns, shaped by racial prejudices, overshadow Floresta's feminism, prohibiting the kind of unifying discourse of motherhood, which she claimed to profess.     

Observation in Political Research: A Qualitative Approach

Qualitative research in politics is predominantly interview-based. Observation is neglected as a research tool by political scientists. This article presents the case for using observation techniques in political research. Drawing from the authors experience of using structured observation to research Chief Executives, the article shows how observation can be included as a valuable part of a qualitative research strategy. It addresses the how, where, when and why of applying observation to political research. The crucial advantage of observation methods is identified as understanding the context and environment in which actions occur and decisions are taken.     

What congressmen knew and when they knew it: Further evidence on the origins of U.S. broadcasting regulation

This paper presents richer contemporaneous evidence of Congress's role in the passage of the Radio Act of 1927, the act which established the basic statutory framework that still governs federal regulation of broadcasting in the United States. Recent analysis finding the court's decision in Tribune Co. v. Oak Leaves Broadcasting Station to have been the cause of Congress's action on the radio bill is shown to rest on an inaccurate chronology of congressional decisionmaking. More closely examining the actions of legislators upon whose votes passage of the radio act depended, this paper contributes new evidence of strategic orchestration surrounding the perceived “chaos of the airwaves” that stimulated broadcasting regulation. Original congressional documents show that, in a political context characterized by costly information, intra-congressional manipulation of information costs was an important factor in the adoption of the Radio Act of 1927. Personal ties between executive branch officials are shown to have spawned a key legal opinion that prompted passage of the radio bill.