Checking Normality and Homoscedasticity in the General Linear Model Using Diagnostic Plots

Inference for the general linear model makes several assumptions, including independence of errors, normality, and homogeneity of variance. Departure from the latter two of these assumptions may indicate the need for data transformation or removal of outlying observations. Informal procedures such as diagnostic plots of residuals are frequently used to assess the validity of these assumptions or to identify possible outliers. A simulation-based approach is proposed, which facilitates the interpretation of various diagnostic plots by adding simultaneous tolerance bounds. Several tests exist for normality or homoscedasticity in simple random samples. These tests are often applied to residuals from a linear model fit. The resulting procedures are approximate in that correlation among residuals is ignored. The simulation-based approach accounts for the correlation structure of residuals in the linear model and allows simultaneously checking for possible outliers, non normality, and heteroscedasticity, and it does not rely on formal testing.

[Supplementary materials are available for this article. Go to the publisher's online edition of Communications in Statistics—Simulation and Computation® for the following three supplemental resource: a word file containing figures illustrating the mode of operation for the bisectional algorithm, QQ-plots, and a residual plot for the mussels data.]     

Sluts that Choose Vs Doormat Gypsies

The UK primetime series My Big Fat Gypsy Wedding (Channel 4, 2010, 2011, 2012) offered audiences the opportunity to be armchair matrimonial ethnographers, to reveal the courtship curiosities of “one of the most secretive communities in the UK.” In spite of claims to social realist documentary, however, we argue that this programme has clearer resonances with “sexposé” reality television, producing and circulating a moral, visual economy premised upon the cultural figuration of “the gypsy bride.” The gypsy girl and gypsy bride are marked as victims of male gypsy oppression, of “backwards” and repressive cultural practices, of age-inappropriate sexualisation and “excessive” consumerism, and is thus defined by her failure to be a good aspirational postfeminist subject. In this paper, we explore the intersecting discourses around gender, sexuality, class, and race operative within Gypsy Wedding and analyse online forums responding to the programme. We use psychosocial methodologies and theories of affect to argue that the gypsy bride becomes a figure of abjection, desired and despised, and that the (readily accepted) invitation to be appalled by her “oppression” reveals the strategic potency of postfeminist notions of empowerment and the racist, sexist, and classist agendas it can serve.     

“Responsiveness of mature oak trees (Quercus robur L.) to soil water dynamics and meteorological constraints in urban environments”

Urban Ecosystems - Urban trees contribute to the regulation of microclimates of cities through transpirational cooling. The main environmental factors determining transpiration are evaporative...     

Stepfamily Processes and Youth Adjustment: The Role of Perceived Neighborhood Collective Efficacy

Using a representative sample from the National Longitudinal Study of Adolescent to Adult Health and a recently developed stepfamily‐process typology, this study explores three plausible functions of perceived neighborhood collective efficacy with respect to stepfamily life and youth adjustment: an ability to (1) prevent maladaptive patterns of stepfamily processes, (2) promote stepchildren's adjustment beyond the influence of stepfamily processes, and (3) protect stepchildren's adjustment when faced with maladaptive patterns of stepfamily processes. The results indicate that higher levels of perceived neighborhood collective efficacy are associated with more adaptive stepfamily processes and higher levels of youth self‐esteem over time, net the influence of stepfamily processes.     

Terrorism‐Centric Behaviors and Adversarial Threat Awareness*

This article estimates situational awareness in a diverse collection of police officers with respect to their individual ability to identify nine key behaviors that are indicative of terrorism activity. The selected group of police officers was drawn from state, county, and municipal law enforcement organizations. The terrorist‐centric behaviors were presented to the test group in multicomponent text‐based scenarios that emulate real‐world police events and respondents were instructed to rate each scenario component on an 11‐point Likert‐type suspicion scale. With the exception of terrorist fundraising, law enforcement personnel tended to view all of the terrorist‐centric activities and behaviors as at least “somewhat suspicious.” The activities that could also be associated with “conventional” criminality such as weapons acquisition received higher ratings than those activities more exclusively related to terrorism such as recruiting. We also noted statistically significant differences based on agency type, officers’ assignment (patrol or detective), experience, gender, agency size, and education. Race had no effect.     

Access to Health Care: Social Determinants of Preventive Cancer Screening Use in Northern British Columbia

The purpose of this study was to examine theextent to which social factors are influentialin determining women's access to cancerscreening services in Prince George, BritishColumbia. Specifically, this study evaluatedthe association of age, income, education, workstatus, disability, marital status, andimmigrant status with previous use of screeningmammography and Pap tests. Data was obtainedfrom the 1994 National Population HealthSurvey, which contains a sample of 416 womenfrom the Prince George area. A series oflogistic regression analyses were used todistinguish ever versus never beenscreened as well as recency of previousscreening. Participation rates in screeningmammography in Prince George are comparativelyhigh; however, no association was found betweensocial factors and previous mammography use.This suggests women in Prince George areparticipating in mammography servicesregardless of social background. Participationrates in Pap test screening in Prince Georgeare high and are similar to provincialaverages; however, while a large percentage ofwomen have been screened, this percentagevaries across social groups. Immigrant women,single women, and women with less education areover represented among women who have never hada Pap test. In addition, older women are lesslikely to obtain a recent Pap test whencompared to younger women. This study suggeststhat certain groups of women in northernBritish Columbia experience low participationin health services, resulting in a higher riskfor poor health and a poor quality of life.     

Voluntarism in Urban Regeneration: Civic,Charity or Hybrid? Experiences from Danish Area-Based Interventions

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Area-based initiatives (ABIs) is a frequently used strategy within contemporary urban regeneration policies to tackle...