Sample sizes for estimation in clinical research

A sample size justification should be given for all clinical investigations. However, sometimes the objective of a trial is to estimate an effect with a view to planning a later definitive study. This paper describes the calculations for designing studies where one wishes to adopt an estimation approach through using confidence intervals around the overall response. Calculations are given for data anticipated to take a Normal form. Copyright © 2004 John Wiley & Sons, Ltd.     

Refined Inference on Long Memory in Realized Volatility

There is an emerging consensus in empirical finance that realized volatility series typically display long range dependence with a memory parameter (d) around 0.4 (Andersen et al., 2001; Martens et al., 2004). The present article provides some illustrative analysis of how long memory may arise from the accumulative process underlying realized volatility. The article also uses results in Lieberman and Phillips (2004, 2005) to refine statistical inference about d by higher order theory. Standard asymptotic theory has an O(n^-1/2) error rate for error rejection probabilities, and the theory used here refines the approximation to an error rate of o(n^-1/2). The new formula is independent of unknown parameters, is simple to calculate and user-friendly. The method is applied to test whether the reported long memory parameter estimates of Andersen et al. (2001) and Martens et al. (2004) differ significantly from the lower boundary (d = 0.5) of nonstationary long memory, and generally confirms earlier findings.     

Pen Dudley''s name finally disappears from the public relations marquee

When the public relations firm D-A-Y was dissolved into Ogilvy & Mather Public Relations November 1, 1988, the longest lived public relations agency disappeared into the sands of time that enveloped the first four agencies started in the first decade of the waning century. The D in D-A-Y stood for Pendleton Dudley, a venerable pioneer in this vocation, who had opened his agency in Wall Street in 1909 at the urging of his good friend, Ivy Lee. Dudley, a rugged, independent product of frontier America, headed his firm for fifty-seven years—a longevity record surpassed only by that of Edward L. Bernays, who started his firm in 1919 in the Post World War I public relations boom.Pendleton Dudley—known to his close friends as Pen and to his associates in his firm as PD, was born September 8, 1876, in a small frontier town of Troy, Missouri, when America was an agricultural nation. He came to pioneer as a counselor to the corporate giants, AT&T among them, in a complex, interdependent corporate industrial America. Pen Dudley did much to infuse this field with respectability in a time when it was viewed with suspicion or disdain in its early years. He was a strong advocate of research as the only sound basis for planning and executing programs to influence public behavior. He was also active in the Public Relations Society of America after it was formed in 1948 and was in the forefront of those creating the now extinct Foundation for Public Relations Research and Education. In 1965, he received the Distinguished Service Award from the New York PRSA Chapter. He died at the age of 90 in 1966.The author is Dean Emeritus of Journalism at the University of Georgia, and co-author Effective Public Relations, 6th Ed.     

SOCIOECONOMIC STATUS, JOB CONDITIONS, AND WELL-BEING: Self-Concept Explanations for Gender-Contingent Effects

Using data from a representative sample of adults age eighteen to fifty‐five who reside in Toronto, Canada, and are employed in the paid labor force, this study asks: Are the health benefits of education, income, job autonomy, and nonroutinized work different for women and men? If so, do mastery and self‐esteem contribute to those differences? Results show that women and men derive different personal benefits from socioeconomic status and job qualities: (1) education, job autonomy, and nonroutinized work are associated more positively with the sense of mastery among women, (2) job autonomy is associated more positively with self‐esteem among women, (3) education, job autonomy, and nonroutinized work are associated more negatively with depressive symptoms among women, and (4) job autonomy and nonroutinized work are associated more positively with global health among women. Moreover, the patterns in (1) and (2) explain the gender‐contingent effects in (3) and (4). In addition, unexpected suppression effects reveal that, among men, education is associated negatively with mastery and self‐esteem—but only after adjustment for job conditions. I interpret the findings in the context of the disadvantaged status thesis and speculate about status‐related social comparison processes.     

Classifying At‐Risk High School Youth: The Influence of Exposure to Community Violence and Protective Factors on Academic and Health Outcomes

Using cluster analysis, 789 predominately Latino and African American high school youth were classified into varying academic at‐risk profiles using self‐reported levels of academic confidence, motivation to attend school, perceived family support, connections with teachers and peers, and exposure to violence. Six clusters emerged, 5 of which were identified as “at‐risk.” The clusters were examined in relation to academic stress, health status, grades, and school retention. Exposure to violence was one distinguishing feature of youth identified as most vulnerable, vulnerable, and resilient; however, youth identified as resilient recorded better academic outcomes.     

Issues in applying recent CPMP ‘Points to Consider’ and FDA guidance documents with biostatistical implications

The International Conference on Harmonisation guideline ‘Statistical Principles for Clinical Trials’ was adopted by the Committee for Proprietary Medicinal Products (CPMP) in March 1998, and consequently is operational in Europe. Since then more detailed guidance on selected topics has been issued by the CPMP in the form of ‘Points to Consider’ documents. The intent of these was to give guidance particularly to non‐statistical reviewers within regulatory authorities, although of course they also provide a good source of information for pharmaceutical industry statisticians. In addition, the Food and Drug Administration has recently issued a draft guideline on data monitoring committees. In November 2002 a one‐day discussion forum was held in London by Statisticians in the Pharmaceutical Industry (PSI). The aim of the meeting was to discuss how statisticians were responding to some of the issues covered in these new guidelines, and to document consensus views where they existed. The forum was attended by industry, academic and regulatory statisticians. This paper outlines the questions raised, resulting discussions and consensus views reached. It is clear from the guidelines and discussions at the workshop that the statistical analysis strategy must be planned during the design phase of a clinical trial and carefully documented. Once the study is complete the analysis strategy should be thoughtfully executed and the findings reported. Copyright © 2003 John Wiley & Sons, Ltd.