The Danger of Testing by Selecting Controlled Subsets, with Applications to Spoken-Word Recognition

When examining the effects of a continuous variable 'x' on an outcome 'y', a researcher might choose to dichotomize on 'x', dividing the population into two sets—low 'x' and high 'x'—and testing whether these two subpopulations differ with respect to 'y'. Dichotomization has long been known to incur a cost in statistical power, but there remain circumstances in which it is appealing: an experimenter might use it to control for confounding covariates through subset selection, by carefully choosing a subpopulation of Low and a corresponding subpopulation of High that are balanced with respect to a list of control variables, and then comparing the subpopulations’ 'y' values. This “divide, select, and test” approach is used in many papers throughout the psycholinguistics literature, and elsewhere. Here we show that, despite the apparent innocuousness, these methodological choices can lead to erroneous results, in two ways. First, if the balanced subsets of Low and High are selected in certain ways, it is possible to conclude a relationship between 'x' and 'y' not present in the full population. Specifically, we show that previously published conclusions drawn from this methodology—about the effect of a particular lexical property on spoken-word recognition—do not in fact appear to hold. Second, if the balanced subsets of Low and High are selected randomly, this methodology frequently fails to show a relationship between 'x' and 'y' that is present in the full population. Our work uncovers a new facet of an ongoing research effort: to identify and reveal the implicit freedoms of experimental design that can lead to false conclusions

Mental health consultations in a prison population: a descriptive study

BACKGROUND: The psychiatric morbidity among prison inmates is substantially higher than in the general population. We do, however, have insufficient knowledge about the extent of psychiatric treatment provided in our prisons. The aim of the present study was to give a comprehensive description of all non-pharmacological interventions provided by the psychiatric health services to a stratified sample of prison inmates. METHODS: Six medium/large prisons (n = 928) representing 1/3 of the Norwegian prison population and with female and preventive detention inmates over-sampled, were investigated cross-sectionally. All non-pharmacological psychiatric interventions, excluding pure correctional programs, were recorded. Those receiving interventions were investigated further and compared to the remaining prison population. RESULTS: A total of 230 of the 928 inmates (25 %) had some form of psychiatric intervention: 184 (20 %) were in individual psychotherapy, in addition 40 (4 %) received ad hoc interventions during the registration week. Group therapy was infrequent (1 %). The psychotherapies were most often of a supportive (62 %) or behavioural-cognitive (26 %) nature. Dynamic, insight-oriented psychotherapies were infrequent (8 %). Concurrent psychopharmacological treatment was prevalent (52 %). Gender and age did not correlate with psychiatric interventions, whereas prisoner category (remanded, sentenced, or preventive detention) did (p < 0.001). Most inmates had a number of defined problem areas, with substance use, depression, anxiety, and personality disorders most prevalent. Three percent of all inmates were treated for a psychotic disorder. Remand prisoners averaged 14 sessions per week per 100 inmates, while sentenced inmates and those on preventive detention averaged 22 and 25 sessions per week per 100 inmates, respectively. Five out of six psychiatric health services estimated the inmates' psychiatric therapy needs as adequately met, both overall and in the majority of individual cases. CONCLUSION: Our results pertain only to prisons with adequate primary and mental health services and effective diversion from prison of individuals with serious mental disorders. Given these important limitations, we do propose that the service estimates found may serve as a rough guideline to the minimum number of sessions a prison's psychiatric health services should be able to fulfil in order to serve the inmates psychiatric needs. The results rely on the specialist services' own estimates only. Future studies should take other important informants, including the inmates themselves, into consideration

An argument against the focus on Community Resilience in Public Health

Background - It has been suggested that Public Health professionals focus on community resilience in tackling chronic problems, such as poverty and deprivation; is this approach useful? Discussion - Resilience is always i) of something ii) to something iii) to an endpoint, as in i) a rubber ball, ii) to a blunt force, iii) to its original shape. “Community resilience” might be: of a neighbourhood, to a flu pandemic, with the endpoint, to return to normality. In these two examples, the endpoint is as-you-were. This is unsuitable for some examples of resilience. A child that is resilient to an abusive upbringing has an endpoint of living a happy life despite that upbringing: this is an as-you-should-be endpoint. Similarly, a chronically deprived community cannot have the endpoint of returning to chronic deprivation: so what is its endpoint? Roughly, it is an as-you-should-be endpoint: to provide an environment for inhabitants to live well. Thus resilient communities will be those that do this in the face of challenges. How can they be identified? One method uses statistical outliers, neighbourhoods that do better than would be expected on a range of outcomes given a range of stressors. This method tells us that a neighbourhood is resilient but not why it is. In response, a number of researchers have attributed characteristics to resilient communities; however, these generally fail to distinguish characteristics of a good community from those of a resilient one. Making this distinction is difficult and we have not seen it successfully done; more importantly, it is arguably unnecessary. There already exist approaches in Public Health to assessing and developing communities faced with chronic problems, typically tied to notions such as Social Capital. Communityresilience to chronic problems, if it makes sense at all, is likely to be a property that emerges from the various assets in a community such as human capital, built capital and natural capital. Summary - Public Health professionals working with deprived neighbourhoods would be better to focus on what neighbourhoods have or could develop as social capital for living well, rather than on the vague and tangential notion of community resilience.</p

Fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin with gemtuzumab ozogamicin improves event-free survival in younger patients with newly diagnosed aml and overall survival in patients with npm1 and flt3 mutations

Purpose To determine the optimal induction chemotherapy regimen for younger adults with newly diagnosed AML without known adverse risk cytogenetics. Patients and Methods One thousand thirty-three patients were randomly assigned to intensified (fludarabine, cytarabine, granulocyte colony-stimulating factor, and idarubicin [FLAG-Ida]) or standard (daunorubicin and Ara-C [DA]) induction chemotherapy, with one or two doses of gemtuzumab ozogamicin (GO). The primary end point was overall survival (OS). Results There was no difference in remission rate after two courses between FLAG-Ida + GO and DA + GO (complete remission [CR] + CR with incomplete hematologic recovery 93% v 91%) or in day 60 mortality (4.3% v 4.6%). There was no difference in OS (66% v 63%; P = .41); however, the risk of relapse was lower with FLAG-Ida + GO (24% v 41%; P < .001) and 3-year event-free survival was higher (57% v 45%; P < .001). In patients with an NPM1 mutation (30%), 3-year OS was significantly higher with FLAG-Ida + GO (82% v 64%; P = .005). NPM1 measurable residual disease (MRD) clearance was also greater, with 88% versus 77% becoming MRD-negative in peripheral blood after cycle 2 (P = .02). Three-year OS was also higher in patients with a FLT3 mutation (64% v 54%; P = .047). Fewer transplants were performed in patients receiving FLAG-Ida + GO (238 v 278; P = .02). There was no difference in outcome according to the number of GO doses, although NPM1 MRD clearance was higher with two doses in the DA arm. Patients with core binding factor AML treated with DA and one dose of GO had a 3-year OS of 96% with no survival benefit from FLAG-Ida + GO. Conclusion Overall, FLAG-Ida + GO significantly reduced relapse without improving OS. However, exploratory analyses show that patients with NPM1 and FLT3 mutations had substantial improvements in OS. By contrast, in patients with core binding factor AML, outcomes were excellent with DA + GO with no FLAG-Ida benefit

Assignment Games with Conflicts: Robust Price of Anarchy and Convergence Results via Semi-Smoothness

We study assignment games in which jobs select machines, and in which certain pairs of jobs may conflict, which is to say they may incur an additional cost when they are both assigned to the same machine, beyond that associated with the increase in load. Questions regarding such interactions apply beyond allocating jobs to machines: when people in a social network choose to align themselves with a group or party, they typically do so based upon not only the inherent quality of that group, but also who amongst their friends (or enemies) chooses that group as well. We show how semi-smoothness, a recently introduced generalization of smoothness, is necessary to find tight bounds on the robust price of anarchy, and thus on the quality of correlated and Nash equilibria, for several natural job-assignment games with interacting jobs. For most cases, our bounds on the robust price of anarchy are either exactly 2 or approach 2. We also prove new convergence results implied by semi-smoothness for our games. Finally we consider coalitional deviations, and prove results about the existence and quality of strong equilibrium