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Uniformity of content requirements for tablets and capsules.

Present pharmacopoeial requirements for uniformity of content of tablets and capsules are based on tests by attributes. A test for uniformity of content based on the root mean square deviation about target (ST) is more reliable than the pharmacopoeial tests and has the added convenience of using a single statistic to control both the mean content and the variation about the mean. Implications of the use of the statistic ST in uniformity requirements are discussed.

Capsules↗

Biostatistics in otolaryngology journals.

Clinical research depends on biostatistics to form meaningful inferences from uncertain data. We performed a cross-sectional analysis of clinical research in otolaryngology journals to identify trends in statistical usage and determine the statistical aptitude expected of journal readers. Statistical content and study design were assessed for 1262 articles from 1969, 1979, and 1989. General trends toward an increasing use of inferential statistics and stronger study designs were observed. The number of analytic and experimental studies employing inferential statistics has risen from 20 (31%) in 1969 to 145 (65%) in 1989. Although familiarity with only five statistical techniques gave access to 90% of current articles, this study suggests that the level of statistical expertise demanded of both researchers and readers will continue to increase.

Bibliometrics↗

The role of education in biostatistical consulting.

Medical students, residents, postdoctoral fellows, and faculty commonly consult with biostatistical experts about study design and data analysis when conducting clinical research. The role of biostatistical training during these consultations is examined, and characterizations of the connections between biostatistical consultation and education are reviewed. The presence and kinds of teaching efforts during biostatistical consults at four academic research institutions over various periods of time between 1999 and 2005 (237 consultations in total) were recorded and are described. By site, 67, 70, 78, and 100 per cent of the consulting sessions included biostatistical training, with an overall 78 per cent (95 per cent CI: 73-83 per cent) of consultations including an educational component when all consultations were combined. Training covered a wide range of biostatistical topics. Seventy-five per cent of the consultations with faculty (120/161), 79 per cent with fellows and residents (31/39), and 100 per cent with medical students (10/10) included some degree of instruction in study design or statistical analysis topics. Results show that both the need and the opportunity exist for specialized biostatistical instruction during one-on-one sessions between a consulting biostatistician and physicians, medical students, and research staff. Academic researchers are ideally positioned to absorb this kind of training when they initiate a request for assistance with their own research project.

Biometry↗

Editors can lead researchers to confidence intervals, but can't make them think: statistical reform lessons from medicine.

Since the mid-1980s, confidence intervals (CIs) have been standard in medical journals. We sought lessons for psychology from medicine's experience with statistical reform by investigating two attempts by Kenneth Rothman to change statistical practices. We examined 594 American Journal of Public Health (AJPH) articles published between 1982 and 2000 and 110 Epidemiology articles published in 1990 and 2000. Rothman's editorial instruction to report CIs and not p values was largely effective: In AJPH, sole reliance on p values dropped from 63% to 5%, and CI reporting rose from 10% to 54%; Epidemiology showed even stronger compliance. However, compliance was superficial: Very few authors referred to CIs when discussing results. The results of our survey support what other research has indicated: Editorial policy alone is not a sufficient mechanism for statistical reform. Achieving substantial, desirable change will require further guidance regarding use and interpretation of CIs and appropriate effect size measures. Necessary steps will include studying researchers' understanding of CIs, improving education, and developing empirically justified recommendations for improved statistical practice.

Biomedical Research↗

Use of check lists in assessing the statistical content of medical studies.

Two check lists are used routinely in the statistical assessment of manuscripts submitted to the "BMJ." One is for papers of a general nature and the other specifically for reports on clinical trials. Each check list includes questions on the design, conduct, analysis, and presentation of studies, and answers to these contribute to the overall statistical evaluation. Only a small proportion of submitted papers are assessed statistically, and these are selected at the refereeing or editorial stage. Examination of the use of the check lists showed that most papers contained statistical failings, many of which could easily be remedied. It is recommended that the check lists should be used by statistical referees, editorial staff, and authors and also during the design stage of studies.

Clinical Trials as Topic↗

Effect of DRGs on research.

The author examines the present and potential impact of prospective payment systems and DRGs on research. DRGs are affecting the funding and direction of research. In addition, DRGs may already be affecting the statistical data bases used in research.

Diagnosis-Related Groups↗

Application of new two-sample tests to data from a randomized placebo-controlled heart-failure trial.

In a randomized placebo-controlled double-blind trial of 230 congestive heart failure patients, four treatments were evaluated for efficacy, with exercise tolerance time (ETT) as the primary outcome. Various two-sample tests were applied to the analysis of ETT data. It is shown in this paper that the conventional two-sample tests (t and rank-sum) are insensitive to situations where the effect of the experimental therapy is not consistent across a patient population. Tests recommended by O'Brien are more appropriate for these data. It is also shown that the application of the O'Brien tests led to the identification of sub-groups where the observed effect of the experimental therapy was most pronounced.

Adult↗

A note on the genome scan meta-analysis statistic.

Wise and colleagues (Ann. Hum. Genet. (1999) 63: 263-72) introduced a rank-based statistical technique for meta-analysis of genome scans, the Genome Scan Meta-Analysis (GSMA) method. We provide an alternative derivation of the null distribution of the GSMA statistic, with extensions, and we suggest approximations to the distribution of the GSMA statistic that may be useful in applications.

Chromosome Mapping↗

The trials of clinical trials.

Controlled clinical trials are becoming increasingly frequent in neurology. A review of the literature indicates that several trials have serious flaws in study design and conduct that render the results questionable or uninterpretable. These reports, together with my own experience with the trial of plasmapheresis in the treatment of acute Guillain-Barré syndrome, have led me to conclude that while the formulation of the crucial research question and the definition of outcomes as a measure of efficacy are extremely important, the availability of a compliant patient population of appropriate size and the compliance by the study physicians are essential. Moreover, close cooperation with the statistician in planning the trial and the statistical strategy for analysis is also critical. Suggestions are made to aid the clinician in setting up the most efficacious trial and reporting the results.

Clinical Trials as Topic↗

Statistical power in physical anthropology: a technical report.

A statistical power analysis of The American Journal of Physical Anthropology (Volume 44, 1976) was conducted. Twenty-five articles, which included 3,304 major significance tests, constituted the final sample. Resultant power estimates of 0.38, 0.62, and 0.81, corresponding to small, medium, and large population effects respectively, were obtained. Although the medium effect size estimate falls short of the recommended 0.80 level, the statistical power of physical anthropological research fares well relative to several of the social scientific fields of inquiry.

Anthropology, Physical↗

Use of statistical analysis in the New England Journal of Medicine.

A sorting of the statistical methods used by authors of the 760 research and review articles in Volumes 298 to 301 of The New England Journal of Medicine indicates that a reader who is conversant with descriptive statistics (percentages, means, and standard deviations) has statistical access to 58 per cent of the articles. Understanding t-tests increases this access to 67 per cent. The addition of contingency tables gives statistical access to 73 per cent of the articles. Familiarity with each additional statistical method gradually increases the percentage of accessible articles. Original Articles use statistical techniques more extensively than other articles in the Journal. Research studies based on a longitudinal design make heavier use of statistics than do those using a cross-sectional design. The tabulations in this study should aid clinicians and medical investigators who are planning their continuing education in statistical methods, and faculty who design or teach courses in quantitative methods for medical and health professionals.

Education, Medical, Continuing↗

Satisfied conclusion validity of early intervention research with handicapped children.

The statistical conclusion validity of early intervention research studies was examined by conducting a post hoc power analysis of 484 statistical tests from 49 early intervention articles. Statistical power determinations were made based on Cohen's (1977) criteria for small, medium, and large effect sizes. The analysis revealed that the median power to detect small, medium, and large effect sizes ranged from .08 to .46. Four percent of early intervention studies had adequate power (.80 or greater) to detect medium intervention effects and 18% to detect large intervention effects. The power values suggest poor statistical conclusion validity in the analyzed research and should alert investigators to the possibility of Type II experimental errors in the early intervention research literature. The argument is made that low statistical conclusion validity has practical consequences in relation to program evaluation and cost-effectiveness determinations.

Child, Preschool↗