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Large Sample (large + sample)
Terms modified by Large Sample Selected AbstractsA SPATIAL CLIFF-ORD-TYPE MODEL WITH HETEROSKEDASTIC INNOVATIONS: SMALL AND LARGE SAMPLE RESULTS,JOURNAL OF REGIONAL SCIENCE, Issue 2 2010Irani Arraiz ABSTRACT In this paper, we specify a linear Cliff-and-Ord-type spatial model. The model allows for spatial lags in the dependent variable, the exogenous variables, and disturbances. The innovations in the disturbance process are assumed to be heteroskedastic with an unknown form. We formulate multistep GMM/IV-type estimation procedures for the parameters of the model. We also give the limiting distributions for our suggested estimators and consistent estimators for their asymptotic variance-covariance matrices. We conduct a Monte Carlo study to show that the derived large-sample distribution provides a good approximation to the actual small-sample distribution of our estimators. [source] Mixture cure survival models with dependent censoringJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 3 2007Yi Li Summary., The paper is motivated by cure detection among the prostate cancer patients in the National Institutes of Health surveillance epidemiology and end results programme, wherein the main end point (e.g. deaths from prostate cancer) and the censoring causes (e.g. deaths from heart diseases) may be dependent. Although many researchers have studied the mixture survival model to analyse survival data with non-negligible cure fractions, none has studied the mixture cure model in the presence of dependent censoring. To account for such dependence, we propose a more general cure model that allows for dependent censoring. We derive the cure models from the perspective of competing risks and model the dependence between the censoring time and the survival time by using a class of Archimedean copula models. Within this framework, we consider the parameter estimation, the cure detection and the two-sample comparison of latency distributions in the presence of dependent censoring when a proportion of patients is deemed cured. Large sample results by using martingale theory are obtained. We examine the finite sample performance of the proposed methods via simulation and apply them to analyse the surveillance epidemiology and end results prostate cancer data. [source] On the sensitivity of the restricted least squares estimators to covariance misspecificationTHE ECONOMETRICS JOURNAL, Issue 3 2007Alan T.K. Wan Summary, Traditional econometrics has long stressed the serious consequences of non-spherical disturbances for the estimation and testing procedures under the spherical disturbance setting, that is, the procedures become invalid and can give rise to misleading results. In practice, it is not unusual, however, to find that the parameter estimates do not change much after fitting the more general structure. This suggests that the usual procedures may well be robust to covariance misspecification. Banerjee and Magnus (1999) proposed sensitivity statistics to decide if the Ordinary Least Squares estimators of the coefficients and the disturbance variance are sensitive to deviations from the spherical error assumption. This paper extends their work by investigating the sensitivity of the restricted least squares estimator to covariance misspecification where the restrictions may or may not be correct. Large sample results giving analytical evidence to some of the numerical findings reported in Banerjee and Magnus (1999) are also obtained. [source] Supersoft X-ray sourcesASTRONOMISCHE NACHRICHTEN, Issue 2 2010F. Haberl Abstract The workshop "Supersoft X-ray Sources , New Developments" brought together observers and theoretician to discuss the present status and unsolved problems of supersoft source research. A large part of the workshop was devoted to optical novae and their supersoft state. Large samples of supersoft X-ray sources were presented from nearby galaxies, as well as extensive monitoring campaigns ofbright individual sources. The theoretical modelling oflight curves and high-resolution X-ray spectra are well underway, but details are often not yet understood (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Impact of R&D Intensity on Demand for Specialist Auditor Services,CONTEMPORARY ACCOUNTING RESEARCH, Issue 1 2005JAYNE M. GODFREY Abstract The audit fee research literature argues that auditors' costs of developing brand name reputations, including top-tier designation and recognition for industry specialization, are compensated through audit fee premiums. Audited firms reduce agency costs by engaging high-quality auditors who monitor the levels and reporting of discretionary expenditures and accruals. In this study we examine whether specialist auditor choice is associated with a particular discretionary expenditure - research and development (R&D). For a large sample of U.S. companies from a range of industries, we find strong evidence that R&D intensity is positively associated with firms' choices of auditors who specialize in auditing R&D contracts. Additionally, we find that R&D intensive firms tend to appoint top-tier auditors. We use simultaneous equations to control for interrelationships between dependent variables in addition to single-equation ordinary least squares (OLS) and logistic regression models. Our results are particularly strong in tests using samples of small firms whose auditor choice is not constrained by the need to appoint a top-tier auditor to ensure the auditor's financial independence from the client. [source] Gender and Ethnic Diversity Among UK Corporate BoardsCORPORATE GOVERNANCE, Issue 2 2007Stephen Brammer This paper investigates the ethnic and gender diversity of the corporate board of UK companies, placing particular emphasis on links to board size and industry characteristics. We employ a novel dataset that covers a large sample of UK PLCs and describes a director's gender, ethnicity and position held. We find both ethnic and gender diversity to be very limited, and that diversity is somewhat less pronounced among executive positions. We find significant cross-sector variation in gender diversity, with an above average prevalence of women in Retail, Utilities, Media and Banking, while such variation in ethnic diversity is considerably less pronounced. Our evidence suggests that a close proximity to final consumers plays a more significant role in shaping board diversity than does the female presence among the industry's workforce. We argue that this shows that board diversity is influenced by a firm's external business environment and particularly an imperative to reflect corresponding diversity among its customers. [source] Evaluating the Characteristics of Corporate Boards Associated with Layoff DecisionsCORPORATE GOVERNANCE, Issue 2 2006Alfred Yawson The paper evaluates the characteristics of corporate boards associated with layoff decisions using a large sample of UK firms suffering performance declines over the period 1994,2003. The results show that firms are less likely to respond to performance declines with employee layoffs when they have large boards. Further analysis shows that layoff decisions are positively associated with the proportion of outside directors and directors' remuneration. The findings provide some support to the recommendations of the Cadbury Report (1992) and Higgs Review (2003) on the importance of the structure and composition of board of directors in the corporate governance process. [source] ESTIMATING A DOSE-RESPONSE RELATIONSHIP BETWEEN LENGTH OF STAY AND FUTURE RECIDIVISM IN SERIOUS JUVENILE OFFENDERS,CRIMINOLOGY, Issue 3 2009THOMAS A. LOUGHRAN The effect of sanctions on subsequent criminal activity is of central theoretical importance in criminology. A key question for juvenile justice policy is the degree to which serious juvenile offenders respond to sanctions and/or treatment administered by the juvenile court. The policy question germane to this debate is finding the level of confinement within the juvenile justice system that maximizes the public safety and therapeutic benefits of institutional confinement. Unfortunately, research on this issue has been limited with regard to serious juvenile offenders. We use longitudinal data from a large sample of serious juvenile offenders from two large cities to 1) estimate a causal treatment effect of institutional placement, as opposed to probation, on future rate of rearrest and 2) investigate the existence of a marginal effect (i.e., benefit) for longer length of stay once the institutional placement decision had been made. We accomplish the latter by determining a dose-response relationship between the length of stay and future rates of rearrest and self-reported offending. The results suggest that an overall null effect of placement exists on future rates of rearrest or self-reported offending for serious juvenile offenders. We also find that, for the group placed out of the community, it is apparent that little or no marginal benefit exists for longer lengths of stay. Theoretical, empirical, and policy issues are outlined. [source] SOCIAL ECOLOGY AND RECIDIVISM: IMPLICATIONS FOR PRISONER REENTRY,CRIMINOLOGY, Issue 2 2008DANIEL P. MEARS Despite the marked increase in incarceration over the past 30 years and the fact that roughly two thirds of released offenders are rearrested within 3 years of release, we know little about how the social ecology of the areas to which offenders return may influence their recidivism or whether it disproportionately affects some groups more than others. Drawing on recent scholarship on prisoner reentry and macrolevel predictors of crime, this study examines a large sample of prisoners released to Florida communities to investigate how two dimensions of social ecology,resource deprivation and racial segregation,may independently, and in interaction with specific populations, influence recidivism. The findings suggest that ecology indeed is consequential for recidivism, and it differentially influences some groups more than others. We discuss these findings and their implications for theory, research, and policy. [source] Investigating Academic Success Factors for Undergraduate Business StudentsDECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 2 2008Mehdi Kaighobadi ABSTRACT Student academic performance is of major interest to all stakeholders of higher education institutions. This study questions whether or not statistical analysis of information that is readily available in most universities' official records system can be used to predict overall academic success. In particular, this study is an attempt to understand factors that affect academic success for business students by examining gender, age, ethnicity, and performance in two required core knowledge courses as predictors of academic success for a large sample of undergraduate students at a Association to Advance Collegiate Schools of Business,accredited business school. The results suggest that student performance is significantly related to some basic demographic variables, but the strongest predictors of overall academic success are the grades the students receive in core knowledge courses that are typically taken in the earlier semesters of business students' plans of study. [source] Early adversity in chronic depression: clinical correlates and response to pharmacotherapy,,DEPRESSION AND ANXIETY, Issue 8 2009Daniel N. Klein Ph.D. Abstract Background: There is growing evidence suggesting that early adversity may be a marker for a distinct pathway to major depressive disorder (MDD). We examined associations between childhood adversity and a broad variety of clinical characteristics and response to pharmacotherapy in a large sample of patients with chronic forms of MDD. Methods: Subjects included 808 patients with chronic forms of MDD (chronic MDD, double depression, or recurrent MDD with incomplete recovery between episodes and a total continuous duration of >2 years) who were enrolled in a 12-week open-label trial of algorithm-guided pharmacotherapy. Baseline assessments included a semi-structured diagnostic interview, and clinician- and self-rated measures of depressive symptoms, social functioning, depressotypic cognitions, and personality traits, and childhood adversity. Patients were re-evaluated every 2 weeks. Results: A longer duration of illness; earlier onset; greater number of episodes, symptom severity, self-rated functional impairment, suicidality, and comorbid anxiety disorder; and higher levels of dysfunctional attitudes and self-criticism were each associated with multiple forms of childhood adversity. A history of maternal overcontrol, paternal abuse, paternal indifference, sexual abuse, and an index of clinically significant abuse each predicted a lower probability of remission. Among patients completing the 12-week trial, 32% with a history of clinically significant abuse, compared to 44% without such a history, achieved remission. Conclusions: These findings indicate that a history of childhood adversity is associated with an especially chronic form of MDD that is less responsive to antidepressant pharmacotherapy. Depression and Anxiety, 2009. Published 2009 Wiley-Liss, Inc. [source] Patterns of comorbidity in panic disorder and major depression: findings from a nonreferred sampleDEPRESSION AND ANXIETY, Issue 2 2005Joseph Biederman M.D. Abstract Previous findings in referred adult samples document major depression as having important moderating effects on the patterns of comorbidity for panic disorder and major depression. This study evaluated whether these patterns of comorbidity are moderated by referral bias. Panic disorder (PD) and major depression (MD) were used to predict the risk for comorbid psychiatric disorders and functional outcomes using data from a large sample of adults who had not been ascertained on the basis of clinical referral (N=1,031). Participants were comprehensively assessed with structured diagnostic interview methodology to evaluate childhood and adult comorbid psychiatric disorders. PD increased the risk for anxiety disorders, independently of MD. MD increased the risk for mania, antisocial personality disorder, psychoactive substance use disorder, disruptive behavior disorders, overanxious disorder, social phobia, and generalized anxiety disorder, independently of PD. These results extend to nonreferred samples' previously reported findings documenting that MD has important moderating effects on patterns of comorbidity for PD and indicate that patterns of comorbidity for PD are not due to referral bias. Depression and Anxiety 21:55,60, 2005. © 2005 Wiley-Liss, Inc. [source] Sub-threshold manic symptoms in recurrent major depressive disorder are a marker for poor outcomeACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2009D. J. Smith Objective:, A small but significant proportion of patients with major depressive disorder (MDD) report mild manic symptoms which are below the diagnostic threshold for a hypomanic episode. Method:, We tested for an association between sub-threshold manic symptoms and clinical outcome in almost 600 patients with recurrent MDD who also had no known family history of bipolar disorder. Results:, 9.6% of this large sample had a life-time history of sub-threshold manic symptoms. These patients were significantly more likely to have a history of poor response to antidepressants (OR 2.84; 95% CI 1.23,6.56; P < 0.02) and more likely to have experienced psychosis (OR 2.07; 95% CI 1.05,4.09; P < 0.04). They had also experienced more depressive episodes on average (P = 0.006) and were more likely to have been admitted to hospital (P < 0.03). Conclusion:, Sub-threshold manic symptoms in patients with recurrent MDD may be a useful clinical marker for poor response to antidepressants and a more morbid long-term clinical course. [source] Risk factor control in patients with Type 2 diabetes and coronary heart disease: findings from the Swedish National Diabetes Register (NDR)DIABETIC MEDICINE, Issue 1 2009S. Gudbjörnsdottir Abstract Aims Patients with Type 2 diabetes and coronary heart disease (CHD) are infrequently treated to risk factor targets in current guidelines. We aimed to examine risk factor management and control levels in a large sample of patients with Type 2 diabetes with CHD. Methods This was an observational study of 1612 patients with first incidence of CHD before 2002, and of 4570 patients with first incidence of CHD before 2005, from the Swedish National Diabetes Register (NDR). Results In patients with CHD 1,2 years before follow-up, the achievement of cardiovascular risk factor targets (follow-up 2002/follow-up 2005) was: HbA1c < 7%, 47%/54% (P < 0.01); blood pressure , 130/80 mmHg, 31%/40% (P < 0.001); total cholesterol < 4.5 mmol/l, 47%/60% (P < 0.001); and low-density lipoprotein-cholesterol < 2.5 mmol/l, 49%/65% (P < 0.001). Use of medication: antihypertensives, 90%/94% (P < 0.01); lipid-lowering drugs, 75%/86% (P < 0.001); and aspirin, 85%/89% (P < 0.05). A high prevalence of adverse lifestyle characteristics prevailed (2002/2005): overweight [body mass index (BMI) , 25 kg/m2], 86%/85%; obesity (BMI , 30 kg/m2), 41%/42%; smokers in age group < 65 years, 16,23%/18,19%; as well as waist circumference , 102 cm (men) or , 88 cm (women), 68% in 2005. Conclusions Patients with a combination of Type 2 diabetes and CHD showed an increased use of lipid-lowering drugs over time, corresponding to improving blood lipid levels. A discrepancy existed between the prevalent use of antihypertensive drugs and the low proportion reaching blood pressure targets. Regretfully, a high prevalence of adverse lifestyle characteristics prevailed. Evidence-based therapy with professional lifestyle intervention and drugs seems urgent for improved quality of secondary prevention in these patients. [source] Pathological gambling: an increasing public health problemACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2001Article first published online: 7 JUL 200 Gambling has always existed, but only recently has it taken on the endlessly variable and accessible forms we know today. Gambling takes place when something valuable , usually money , is staked on the outcome of an event that is entirely unpredictable. It was only two decades ago that pathological gambling was formally recognized as a mental disorder, when it was included in the DSM-III in 1980. For most people, gambling is a relaxing activity with no negative consequences. For others, however, gambling becomes excessive. Pathological gambling is a disorder that manifests itself through the irrepressible urge to wager money. This disorder ultimately dominates the gambler's life, and has a multitude of negative consequences for both the gambler and the people they interact with, i.e. friends, family members, employers. In many ways, gambling might seem a harmless activity. In fact, it is not the act of gambling itself that is harmful, but the vicious cycle that can begin when a gambler wagers money they cannot afford to lose, and then continues to gamble in order to recuperate their losses. The gambler's ,tragic flaw' of logic lies in their failure to understand that gambling is governed solely by random, chance events. Gamblers fail to recognize this and continue to gamble, attempting to control outcomes by concocting strategies to ,beat the game'. Most, if not all, gamblers try in some way to predict the outcome of a game when they are gambling. A detailed analysis of gamblers' selfverbalizations reveals that most of them behave as though the outcome of the game relied on their personal ,skills'. From the gambler's perspective, skill can influence chance , but in reality, the random nature of chance events is the only determinant of the outcome of the game. The gambler, however, either ignores or simply denies this fundamental rule (1). Experts agree that the social costs of pathological gambling are enormous. Changes in gaming legislation have led to a substantial expansion of gambling opportunities in most industrialized countries around the world, mainly in Europe, America and Australia. Figures for the United States' leisure economy in 1996 show gross gambling revenues of $47.6 billion, which was greater than the combined revenue of $40.8 billion from film box offices, recorded music, cruise ships, spectator sports and live entertainment (2). Several factors appear to be motivating this growth: the desire of governments to identify new sources of revenue without invoking new or higher taxes; tourism entrepreneurs developing new destinations for entertainment and leisure; and the rise of new technologies and forms of gambling (3). As a consequence, prevalence studies have shown increased gambling rates among adults. It is currently estimated that 1,2% of the adult population gambles excessively (4, 5). Given that the prevalence of gambling is related to the accessibility of gambling activities, and that new forms of gambling are constantly being legalized throughout most western countries, this figure is expected to rise. Consequently, physicians and mental health professionals will need to know more about the diagnosis and treatment of pathological gamblers. This disorder may be under-diagnosed because, clinically, pathological gamblers usually seek help for the problems associated with gambling such as depression, anxiety or substance abuse, rather than for the excessive gambling itself. This issue of Acta Psychiatrica Scandinavica includes the first national survey of problem gambling completed in Sweden, conducted by Volberg et al. (6). This paper is based on a large sample (N=9917) with an impressively high response rate (89%). Two instruments were used to assess gambling activities: the South Oaks Gambling Screen-Revised (SOGS-R) and an instrument derived from the DSM-IV criteria for pathological gambling. Current (1 year) and lifetime prevalence rates were collected. Results show that 0.6% of the respondents were classified as probable pathological gamblers, and 1.4% as problem gamblers. These data reveal that the prevalence of pathological gamblers in Sweden is significantly less than what has been observed in many western countries. The authors have pooled the rates of problem (1.4%) and probable pathological gamblers (0.6%), to provide a total of 2.0% for the current prevalence. This 2% should be interpreted with caution, however, as we do not have information on the long-term evolution of these subgroups of gamblers; for example, we do not know how many of each subgroup will become pathological gamblers, and how many will decrease their gambling or stop gambling altogether. Until this information is known, it would be preferable to keep in mind that only 0.6% of the Swedish population has been identified as pathological gamblers. In addition, recent studies show that the SOGS-R may be producing inflated estimates of pathological gambling (7). Thus, future research in this area might benefit from the use of an instrument based on DSM criteria for pathological gambling, rather than the SOGS-R only. Finally, the authors suggest in their discussion that the lower rate of pathological gamblers obtained in Sweden compared to many other jurisdictions may be explained by the greater availability of games based on chance rather than games based on skill or a mix of skill and luck. Before accepting this interpretation, researchers will need to demonstrate that the outcomes of all games are determined by other factor than chance and randomness. Many studies have shown that the notion of randomness is the only determinant of gambling (1). Inferring that skill is an important issue in gambling may be misleading. While these are important issues to consider, the Volberg et al. survey nevertheless provides crucial information about gambling in a Scandinavian country. Gambling will be an important issue over the next few years in Sweden, and the publication of the Volberg et al. study is a landmark for the Swedish community (scientists, industry, policy makers, etc.). This paper should stimulate interesting discussions and inspire new, much-needed scientific investigations of pathological gambling. Acta Psychiatrica Scandinavica Guido Bondolfi and Robert Ladouceur Invited Guest Editors References 1.,LadouceurR & WalkerM. The cognitive approach to understanding and treating pathological gambling. In: BellackAS, HersenM, eds. Comprehensive clinical psychology. New York: Pergamon, 1998:588 , 601. 2.,ChristiansenEM. Gambling and the American economy. In: FreyJH, ed. Gambling: socioeconomic impacts and public policy. Thousand Oaks, CA: Sage, 1998:556:36 , 52. 3.,KornDA & ShafferHJ. Gambling and the health of the public: adopting a public health perspective. J Gambling Stud2000;15:289 , 365. 4.,VolbergRA. Problem gambling in the United States. J Gambling Stud1996;12:111 , 128. 5.,BondolfiG, OsiekC, FerreroF. Prevalence estimates of pathological gambling in Switzerland. Acta Psychiatr Scand2000;101:473 , 475. 6.,VolbergRA, AbbottMW, RönnbergS, MunckIM. Prev-alence and risks of pathological gambling in Sweden. Acta Psychiatr Scand2001;104:250 , 256. 7.,LadouceurR, BouchardC, RhéaumeNet al. Is the SOGS an accurate measure of pathological gambling among children, adolescents and adults?J Gambling Stud2000;16:1 , 24. [source] The utility of online panel surveys versus computer-assisted interviews in obtaining substance-use prevalence estimates in the NetherlandsADDICTION, Issue 10 2009Renske Spijkerman ABSTRACT Aims Rather than using the traditional, costly method of personal interviews in a general population sample, substance-use prevalence rates can be derived more conveniently from data collected among members of an online access panel. To examine the utility of this method, we compared the outcomes of an online survey with those obtained with the computer-assisted personal interviews (CAPI) method. Design Data were gathered from a large sample of online panellists and in a two-stage stratified sample of the Dutch population using the CAPI method. Setting The Netherlands. Participants The online sample comprised 57 125 Dutch online panellists (15,64 years) of Survey Sampling International LLC (SSI), and the CAPI cohort 7204 respondents (15,64 years). Measurements All participants answered identical questions about their use of alcohol, cannabis, ecstasy, cocaine and performance-enhancing drugs. The CAPI respondents were asked additionally about internet access and online panel membership. Both data sets were weighted statistically according to the distribution of demographic characteristics of the general Dutch population. Findings Response rates were 35.5% (n = 20 282) for the online panel cohort and 62.7% (n = 4516) for the CAPI cohort. The data showed almost consistently lower substance-use prevalence rates for the CAPI respondents. Although the observed differences could be due to bias in both data sets, coverage and non-response bias were higher in the online panel survey. Conclusions Despite its economic advantage, the online panel survey showed stronger non-response and coverage bias than the CAPI survey, leading to less reliable estimates of substance use in the general population. [source] The Entrepreneurial Propensity of WomenENTREPRENEURSHIP THEORY AND PRACTICE, Issue 3 2007Nan Langowitz Entrepreneurship is becoming an increasingly important source of employment for women across many countries. The level of female involvement in entrepreneurial activity, however, is still significantly lower than that of men. We take a behavioral economics approach and, using a large sample of individuals in 17 countries, we investigate what variables influence the entrepreneurial propensity of women and whether those variables have a significant correlation with differences across genders. In addition to demographic and economic variables, we include a number of perceptual variables. Our results show that subjective perceptual variables have a crucial influence on the entrepreneurial propensity of women and account for much of the difference in entrepreneurial activity between the sexes. Specifically, we find that women tend to perceive themselves and the entrepreneurial environment in a less favorable light than men across all countries in our sample and regardless of entrepreneurial motivation. Our results suggest that perceptual variables may be significant universal factors influencing entrepreneurial behavior. [source] Large scale wildlife monitoring studies: statistical methods for design and analysisENVIRONMETRICS, Issue 2 2002Kenneth H. Pollock Abstract Techniques for estimation of absolute abundance of wildlife populations have received a lot of attention in recent years. The statistical research has been focused on intensive small-scale studies. Recently, however, wildlife biologists have desired to study populations of animals at very large scales for monitoring purposes. Population indices are widely used in these extensive monitoring programs because they are inexpensive compared to estimates of absolute abundance. A crucial underlying assumption is that the population index (C) is directly proportional to the population density (D). The proportionality constant, ,, is simply the probability of ,detection' for animals in the survey. As spatial and temporal comparisons of indices are crucial, it is necessary to also assume that the probability of detection is constant over space and time. Biologists intuitively recognize this when they design rigid protocols for the studies where the indices are collected. Unfortunately, however, in many field studies the assumption is clearly invalid. We believe that the estimation of detection probability should be built into the monitoring design through a double sampling approach. A large sample of points provides an abundance index, and a smaller sub-sample of the same points is used to estimate detection probability. There is an important need for statistical research on the design and analysis of these complex studies. Some basic concepts based on actual avian, amphibian, and fish monitoring studies are presented in this article. Copyright © 2002 John Wiley & Sons, Ltd. [source] Multivariate Neuropsychological Prediction of Seizure Lateralization in Temporal Epilepsy Surgical CasesEPILEPSIA, Issue 8 2007Therese A. Keary Summary:,Purpose: Neuropsychological assessment can be of assistance in determining seizure lateralization in cases where EEG and MRI findings do not provide clear lateralizing data. While several studies have examined the lateralizing value of individual neuropsychological measures, clinicians are still in need of a statistically sound method that permits the incorporation of multiple neuropsychological variables to predict seizure lateralization in the individual patient. Method: The present study investigated the lateralizing value of several commonly used neuropsychological measures in a large sample of patients (n = 217) who eventually underwent surgical resection to treat their epilepsy. Side of surgery was used to operationally define seizure lateralization. A comparison of the relative utility of a multivariate versus univariate approach to predict seizure lateralization was conducted in temporal epilepsy cases. Results: The results provide evidence for the incremental validity of neuropsychological measures, other than memory and IQ tests, in the prediction of seizure lateralization in patients with medically intractable epilepsy. These data indicate that a multivariate approach increases the accuracy of prediction of seizure lateralization for temporal lobe epilepsy cases. Conclusion: This study supports the use of a multivariate approach using neuropsychological measures to predict seizure lateralization in temporal epilepsy surgical candidates. Regression formulas are provided to enhance the clinical utility of these findings. [source] The Impact of Managerial Entrenchment on Agency Costs: An Empirical Investigation Using UK Panel DataEUROPEAN FINANCIAL MANAGEMENT, Issue 3 2009Chrisostomos Florackis G3; G32 Abstract This paper empirically investigates the relationship between managerial entrenchment and agency costs for a large sample of UK firms over the period 1999,2005. To measure managerial entrenchment, we use detailed information on ownership and board structures and managerial compensation. We develop a managerial entrenchment index, which captures the extent to which managers have the ability and incentives to expropriate wealth from shareholders. Our findings, which are based on a dynamic panel data analysis, show that there is a strong negative relationship between managerial entrenchment and our inverse proxy for agency costs, namely asset turnover ratio. There is also evidence that short-term debt and dividend payments work as effective corporate governance devices for UK firms. Finally, our findings reveal that agency costs are persistent over time. The results are robust to a number of alternative specifications, including varying measures of managerial entrenchment and agency costs. [source] Backtesting Derivative Portfolios with Filtered Historical Simulation (FHS)EUROPEAN FINANCIAL MANAGEMENT, Issue 1 2002Giovanni Barone-Adesi Filtered historical simulation provides the general framework to our backtests of portfolios of derivative securities held by a large sample of financial institutions. We allow for stochastic volatility and exchange rates. Correlations are preserved implicitly by our simulation procedure. Options are repriced at each node. Overall results support the adequacy of our framework, but our VaR numbers are too high for swap portfolios at long horizons and too low for options and futures portfolios at short horizons. [source] A longitudinal study of cannabis use and mental health from adolescence to early adulthoodADDICTION, Issue 4 2000Rob McGee Aims. To examine the longitudinal association between cannabis use and mental health. Design. Information concerning cannabis use and mental health from 15 to 21 years was available for a large sample of individuals as part of a longitudinal study from childhood to adulthood. Participants. Participants were enrolled in the Dunedin Multidisciplinary Health and Development Study, a research programme on the health, development and behaviour of a large group of New Zealanders born between 1 April 1972 and 31 March 1973. Measurements. Cannabis use and identification of mental disorder was based upon self-report as part of a general assessment of mental health using a standard diagnostic interview. Daily smoking and alcohol use at age 15 were assessed by self-report. Indices of family socio-economic status, family climate and parent - child interaction were formed using information gathered from parent report and behavioural observations over early childhood. Childhood behaviour problems were assessed by parent and teacher report. Attachment to parents was assessed in adolescence. Findings. Cross-sectional associations between cannabis use and mental disorder were significant at all three ages. Both outcome variables shared similar pathways of low socio-economic status and history of behaviour problems in childhood, and low parental attachment in adolescence. Mental disorder at age 15 led to a small but significantly elevated risk of cannabis use at age 18; by contrast, cannabis use at age 18 elevated the risk of mental disorder at age 21. The latter association reflected the extent to which cannabis dependence and other externalizing disorders at age 21 were predicted by earlier level of involvement with cannabis. Conclusions. The findings suggest that the primary causal direction leads from mental disorder to cannabis use among adolescents and the reverse in early adulthood. Both alcohol use and cigarette smoking had independent associations with later mental health disorder. [source] HUMAN STUDY: Heavy drinking relates to positive valence ratings of alcohol cuesADDICTION BIOLOGY, Issue 1 2009Carmen Pulido ABSTRACT A positive family history of alcohol use disorders (FH) is a robust predictor of personal alcohol abuse and dependence. Exposure to problem-drinking models is one mechanism through which family history influences alcohol-related cognitions and drinking patterns. Similarly, exposure to alcohol advertisements is associated with alcohol involvement and the relationship between affective response to alcohol cues and drinking behavior has not been well established. In addition, the collective contribution that FH, exposure to different types of problem-drinking models (e.g. parents, peers) and personal alcohol use have on appraisal of alcohol-related stimuli has not been evaluated with a large sample. We investigated the independent effects of FH, exposure to problem-drinking models and personal alcohol use on valence ratings of alcohol pictures in a college sample. College students (n = 227) completed measures of personal drinking and substance use, exposure to problem-drinking models, FH and ratings on affective valence of 60 alcohol pictures. Greater exposure to non-familial problem-drinkers predicted greater drinking among college students (, = 0.17, P < 0.01). However, personal drinking was the only predictor of valence ratings of alcohol pictures (, = ,0.53, P < 0.001). Personal drinking level predicted valence ratings of alcohol cues over and above FH, exposure to problem-drinking models and demographic characteristics. This suggests that positive affective responses to alcohol pictures are more a function of personal experience (i.e. repeated heavy alcohol use) than vicarious learning. [source] Seronegative myasthenia gravis: comparison of neurophysiological picture in MuSK+ and MuSK, patientsEUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2006L. Padua The aim of this study was to compare the neurophysiological and clinical pictures of a large sample of seronegative myasthenia gravis (SNMG) patients with and without anti-MuSK antibodies. Fifty-two consecutive SNMG patients were retrospectively evaluated. They had undergone an extended neurophysiological evaluation: repetitive nerve stimulation (RNS), single fiber EMG (SFEMG), and electromyography (EMG) with nerve conduction study. A muscle biopsy was performed in 11 of 52 patients, the edrophonium test in 44 of 52 patients and anti-AChR antibodies and anti-MuSK antibodies were tested in all patients. Anti-MuSK antibodies were detected in 25 SNMG patients (48.1%). The number of women in the MuSK+ group was significantly higher (P = 0.01) than in the MuSK, group. Seronegative MuSK+ patients are more severely affected and the deficit often involves the bulbar and the respiratory muscles. No statistically significant differences were observed in the edrophonium test between MuSK+ and MuSK, groups. The RNS test was abnormal in a significantly higher number of MUSK, patients than MUSK+ patients (P < 0.00001). With regard to SFEMG data, MuSK, patients were characterized to have more severe neurophysiological pattern. Our observations showed several differences between the clinical and neurophysiological pictures of MUSK+ and MUSK, patients. [source] The usefulness of self-reported psychopathy-like traits in the study of antisocial behaviour among non-referred adolescentsEUROPEAN JOURNAL OF PERSONALITY, Issue 5 2002Henrik Andershed The present study addresses the question of whether it is possible to use a self-report measure of psychopathic traits on non-referred youth samples to identify a subgroup of problematic youths who are particularly problematic and different from other problem youths. A large sample of eighth-grade, non-referred adolescents, and their parents were assessed. Results showed that the adolescents exhibiting a low-socialized psychopathy-like personality constellation had a more frequent, violent, and versatile conduct-problem profile than other low-socialized and well socialized adolescents. The psychopathy-like adolescents also differed from other poorly socialized adolescents in ways that suggested that their etiological background was different from adolescents with non-psychopathy-like conduct problems. We conclude that self-report measures can indeed be useful for research purposes in subtyping youths with conduct problems. Copyright © 2002 John Wiley & Sons, Ltd. [source] Shareholder Value: Principles, Declarations, and ActionsFINANCIAL MANAGEMENT, Issue 1 2010Claudio Loderer This paper is about shareholder value. We examine whether welfare considerations justify that target and whether competitive markets force firms to pursue it. We also argue that shareholder value is strictly an ill-defined goal. We report evidence from a large sample of listed firms across the world that many managers do not even mention shareholders in their mission statements. However, firms that do disclose a commitment to shareholders seem to perform better in terms of stock price and operating performance. [source] Determinants of Investor Demand for Cross-Listed FirmsFINANCIAL MARKETS, INSTITUTIONS & INSTRUMENTS, Issue 3 2010George Athanassakos G11; G12; G15 By focusing on the decisions of investors to invest in cross-listed stocks, this paper presents new evidence on why we observe striking differences in the percentage of trade in foreign markets for cross-listed stocks. With a large sample of Toronto Stock Exchange (TSX) stocks cross-listed in the U.S. and Canada, we document the effect of investor recognition and risk characteristics on the distribution of trading volume. Firms that are more visible to American investors are traded more heavily in the U.S. At the same time, firms that offer diverse risk characteristics are attractive to Americans. While investors understand the benefits of international diversification, as they are attracted to stocks that are different (e.g., the stock of small firms with few assets in the U.S.), they also seek stocks that provide them with high returns. [source] Deal Size, Bid Premium, and Gains in Bank Mergers: The Impact of Managerial MotivationsFINANCIAL REVIEW, Issue 3 2007Atul Gupta G14; G21; G34 Abstract Do mergers with greater target relative to acquirer size create more value than mergers with smaller relative sized targets? Do larger bid amounts represent wealth transfers from acquirers or do they signal greater expected merger gains? We hypothesize that the relations among aggregate merger gains, relative size, and bid premiums are asymmetric across mergers made by value-enhancing versus value-reducing managers. We use a large sample of bank mergers to test these predictions and find that the value response to different explanatory variables is asymmetric. Our findings provide new insights into how the market values merger bids. [source] Genetic and environmental influences on Anxious/Depression during childhood: a study from the Netherlands Twin RegisterGENES, BRAIN AND BEHAVIOR, Issue 8 2005D. I. Boomsma For a large sample of twin pairs from the Netherlands Twins Register who were recruited at birth and followed through childhood, we obtained parental ratings of Anxious/Depression (A/D). Maternal ratings were obtained at ages 3 years (for 9025 twin pairs), 5 years (9222 pairs), 7 years (7331 pairs), 10 years (4430 pairs) and 12 years (2363 pairs). For 60,90% of the pairs, father ratings were also available. Multivariate genetic models were used to test for rater-independent and rater-specific assessments of A/D and to determine the genetic and environmental influences on individual differences in A/D at different ages. At all ages, monozygotic twins resembled each other more closely for A/D than dizygotic twins, implying genetic influences on variation in A/D. Opposite sex twin pairs resembled each other to same extent as same-sex dizygotic twins, suggesting that the same genes are expressed in boys and girls. Heritability estimates for rater-independent A/D were high in 3-year olds (76%) and decreased in size as children grew up [60% at age 5, 67% at age 7, 53% at age 10 (60% in boys) and 48% at age 12 years]. The decrease in genetic influences was accompanied by an increase in the influence of the shared family environment [absent at ages 3 and 7, 16% at age 5, 20% at age 10 (5% in boys) and 18% at age 12 years]. The agreement between parental A/D ratings was between 0.5 and 0.7, with somewhat higher correlations for the youngest group. Disagreement in ratings between the parents was not merely the result of unreliability or rater bias. Both the parents provided unique information from their own perspective on the behavior of their children. Significant influences of genetic and shared environmental factors were found for the unique parental views. At all ages, the contribution of shared environmental factors to variation in rater-specific views was higher for father ratings. Also, at all ages except age 12, the heritability estimates for the rater-specific phenotype were higher for mother ratings (59% at age 3 and decreasing to 27% at age 12 years) than for father ratings (between 14 and 29%). Differences between children, even as young as 3 years, in A/D are to a large extent due to genetic differences. As children grow up, the variation in A/D is due in equal parts to genetic and environmental influences. Anxious/Depression, unlike many other common childhood psychopathologies, is influenced by the shared family environment. These findings may provide support for why certain family therapeutic approaches are effective in the A/D spectrum of illnesses. [source] Managerial incentives and corporate leverage: evidence from the United KingdomACCOUNTING & FINANCE, Issue 3 2009Chrisostomos Florackis G3; G32 Abstract This paper investigates the effect of managerial incentives and corporate governance on capital structure using a large sample of UK firms during the period 1999,2004. The analysis revolves around the view that managerial incentives are important in determining a firm's leverage. However, we argue that the exact impact of these incentives on leverage is likely to be determined by firm-specific governance characteristics. To conduct our investigation, we construct a simple corporate governance measure using detailed ownership and governance information. We present evidence of a significant non-monotonic relationship between executive ownership and leverage. There is also strong evidence suggesting that corporate governance practices have a significant impact on leverage. More importantly, the results reveal that the nature of the relation between executive ownership and leverage depends on the firm's corporate governance structure. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||