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PubMed2003

Do nurses exercise power in basic care situations?

Power is a matter of authority and control. It can be wielded either consciously or unconsciously, and it can be either overt or latent. Using a structured questionnaire, this study set out to describe nurses' opinions about the exercise of power in basic care situations in both acute and long-term care. The questionnaire was organized into four categories in which items concerned: power in obligatory daily activities; power in activities necessitated by obligatory activities; power in voluntary activities; and power in activities that take into account the patient's characteristics. The samples consisted of 228 nurses from five medical and surgical wards of district hospitals, and 233 nurses from five geriatric units of a community health centre and from one nursing home in Finland. The final response rate was 65% (acute care 76%; long-term care 55%). Data analysis was based on statistical methods. The results showed that, in the nurses' own opinion, negative power is exercised only in certain situations and in the patient's best interest, when for instance there are concerns that something may happen to the patient.

Adult↗
PubMed2006

Meta-analysis supports association between serotonin transporter (5-HTT) and suicidal behavior.

Suicidal behavior, which ranks among the top 10 causes of death worldwide, is an important public-health problem and a psychiatric disorder, which has been the subject of considerable study. Studies have shown association between the serotonin transporter (5-HTT) gene and suicidal behavior, although a proportion of alternative studies have produced contrary results both in terms of positive and negative findings, possibly reflecting inadequate statistical power and the use of different populations. Using the cumulative data from recent years in both European and, more particularly, Asian populations, this updated meta-analysis seeks to examine whether the aggregate data provide evidence of statistical significance, and to clarify the contradictory findings suggested by previous studies. It covers all published studies using multiple research methods up to January 2006. Compared with a previous meta-analysis, which found no association between the 5-HTTLPR polymorphism and suicidal behavior (P=0.38), the current results (39 studies) suggest a significant association with a P-value of 0.0068 (overall odds ratio=0.88 (0.8,0.97)), and supports the involvement of the brain 5-HTT in the pathogenesis of suicidal behavior.

Depressive Disorder↗
PubMed2006

G-protein beta3 subunit gene variant is unlikely to have a significant influence on serum uric acid level in Japanese workers.

The C825T variant of the G-protein beta3 subunit (GNB3) gene has attracted renewed attention as a candidate gene for obesity, hypertension and hyperuricemia. The main role of G-protein is to translate signals from the cell surface into a cellular response. The 825T allele is associated with a splice variant of GNB3 protein and enhanced G-protein activation. We examined the relationship between this variant and the risk of hyperuricemia in Japanese workers. The study subjects were 1,452 men and 1,169 women selected from 3,834 men and 2,591 women in 1997. On the basis of common clinical criteria, hyperuricemia I was defined as serum uric acid >or= 7.0 mg/dl in men and 6.0 mg/dl in women or taking antihyperuricemic medication. The hyperuricemia I group consisted of 186 men and 20 women and its control of 1,266 men and 1,149 women. Hyperuricemia II was defined as serum uric acid > 5.7 mg/dl (median) in men and 3.9 mg/dl (median) in women or taking antihyperuricemic medication. The hyperuricemic II group consisted of 684 men and 570 women and its control of 768 men and 599 women. To replicate previous significant results in young Caucasian men, we selected these criteria because the authors of the study in young Caucasian men adopted the median in their subjects as a cut-off. The statistical power was estimated as 99% based on the significant results in Caucasians. Genotype and allele distributions in men and women with hyperuricemia I and II were not significantly different from those in the corresponding control groups. Logistic regression analysis on hyperuricemia I and II, and multiple regression on serum uric acid level demonstrated no significant effect of the C825T genotype. Despite the sufficient statistical power, this study could not demonstrate the significant influence of C825T on hyperuricemia or serum uric acid. The targeting of this polymorphism is unlikely to be beneficial in the prevention of hyperuricemia in the general Japanese population.

Cross-Sectional Studies↗
PubMed1997

A triarchical model of batting abilities: applying psychological statistics to baseball.

A triarchical model of batting ability in baseball (Power, Skill, and Speed) was hypothesized. Factor analysis of data obtained from 77 players on the four 1996 playoff teams produced three meaningful oblique factors, giving support to the proposed model. The factor structure and specific pattern of factor loading were quite stable as coefficients of congruence of .97 to .99 were obtained between factors extracted from separate analyses of the National League players (n = 38) and the American League players (n = 39).

Baseball↗
PubMedDate not supplied

Meta-analysis of 2-treatment clinical trials including both continuous and dichotomous results.

To expedite the timely creation of medical practice guidelines, a meta-analytic method was developed to combine both dichotomous survival data and continuous physiologic data from multiple studies of differing experimental design, which compare the same innovative clinical intervention to standard care. An aggregate ratio, R*, of the observed treatment effect to a clinically optimal treatment effect for studies in a series is computed and compared to the 95% confidence limit for R* under the null hypothesis. Input data for continuous variables include sample means, standard errors, and sample sizes. Input data for dichotomous variables include group proportions and sizes. The analysis can be done using a simple, 1-page spreadsheet. It allows one to judge biological significance, to test for statistical significance, to compare subgroups of studies, to test for outliers, and to compute the power of the meta-analysis. These features are demonstrated for studies of interposed abdominal compression-cardiopulmonary resuscitation.

Abdomen↗
PubMed1995

Meta-analytic comparison of the components of visual cognition in Parkinson's disease.

Controversy surrounds the presence of deficits of visual cognition in Parkinson's Disease. This literature has been seriously undermined by a number of methodological and theoretical faults that make interpretation of this hypothesis difficult. This review proposes a structure of visual cognition composed of 13 aspects. A meta-analysis of these components on 70 studies that used standardised neuropsychological tests and an appropriate normal control group indicates that the PD subjects are significantly compromised on tests of attention and concentration, complex visuospatial functions, and multifactorial spatial functions. More detailed analysis of the basic components of visual cognition was not undertaken due to low statistical power; hence, it remains unclear whether these subjects have primary visual processing deficits in association with their higher order deficits. The observed deficits may be interpreted as being a consequence of either undetermined lower level visual cognitive deficits or a compromise in executive functioning.

Adult↗
PubMed2004

Meta-analysis of linkage studies for complex diseases: an overview of methods and a simulation study.

Linkage genome scans for complex diseases have low power with the usual sample sizes, and hence meta-analysis of several scans for the same disease might be a promising approach. Appropriate data are now becoming accessible. Here we give an overview of the available statistical methods and current applications. In a simulation study, we compare the power of different methods to combine multipoint linkage scores, namely Fisher's p-value combination, the truncated product method, the Genome Search Meta-Analysis (GSMA) method and our weighting methods. In particular, we investigate the effects of heterogeneity introduced by different genetic marker sets and sample sizes between genome scans. The weighting methods explicitly take those differences into account and have more power in the simulated scenarios than the other methods.

Genetic Diseases, Inborn↗
PubMed2006

Spatially filtered magnetoencephalographic analysis of cortical oscillatory changes in basic brain rhythms during the Japanese 'Shiritori' Word Generation Task.

BACKGROUND: 'Shiritori' (capping verses) is a traditional Japanese word generation game, and is very familiar to native Japanese speakers. The shiritori task is expected to more strongly activate temporal language-related regions than conventional word generation to letters because of its characteristic way to make cue letters. OBJECTIVES: The aim of this study was to examine the cortical oscillatory changes in basic brain rhythms during silently performing a shiritori task. METHODS: Using synthetic aperture magnetometry (SAM) analysis of magnetoencephalography, we estimated the tomographic distributions of the statistically significant differences of the power in the alpha and beta frequency bands between the resting and the task periods. RESULTS: Significant event-related desynchronization (ERD) in the 8- to 25-Hz band, thought to reflect neural activation, was localized within task-related cortical regions with left-side dominance. The significant ERDs were estimated in both the frontal and temporal language-related regions encompassing Broca's and Wernicke's areas, although previous neuroimaging studies using word generation to letters showed neural activation predominantly in frontal regions. CONCLUSIONS: Our results show the potential of SAM analysis for reliable brain mapping of language processing, and suggest that the shiritori task might be more suitable for examining the language-related network in the brain than conventional word generation to letters.

Adult↗
PubMed1989

Screening for possible human carcinogens and mutagens. False positives, false negatives: statistical implications.

A screening method aimed at identifying potential human carcinogens using either animal cancer bioassays or short-term genotoxic assays has 4 possible results: true positive, true negative, false positive and false negative. Such a categorisation is superficially similar to the results of hypothesis testing in a statistical analysis. In this latter case the false positive rate is determined by the significance level of the test and the false negative rate by the statistical power of the test. Although the two types of categorisation appear somewhat similar, different statistical issues are involved in their interpretation. Statistical methods appropriate for the analysis of the results of a series of assays include the use of Bayes' theorem and multivariate methods such as clustering techniques for the selection of batteries of short-term test capable of a better prediction of potential carcinogens. The conclusions drawn from such studies are dependent upon the estimates of values of sensitivity and specificity used, the choice of statistical method and the nature of the data set. The statistical issues resulting from the analysis of specific genotoxicity experiments involve the choice of suitable experimental designs and appropriate analyses together with the relationship of statistical significance to biological importance. The purpose of statistical analysis should increasingly be to estimate and explore effects rather than for formal hypothesis testing.

Bayes Theorem↗
PubMed1997

Melanie II--a third-generation software package for analysis of two-dimensional electrophoresis images: I. Features and user interface.

Although two-dimensional electrophoresis (2-DE) computer analysis software packages have existed ever since 2-DE technology was developed, it is only now that the hardware and software technology allows large-scale studies to be performed on low-cost personal computers or workstations, and that setting up a 2-DE computer analysis system in a small laboratory is no longer considered a luxury. After a first attempt in the seventies and early eighties to develop 2-DE analysis software systems on hardware that had poor or even no graphical capabilities, followed in the late eighties by a wave of innovative software developments that were possible thanks to new graphical interface standards such as XWindows, a third generation of 2-DE analysis software packages has now come to maturity. It can be run on a variety of low-cost, general-purpose personal computers, thus making the purchase of a 2-DE analysis system easily attainable for even the smallest laboratory that is involved in proteome research. Melanie II 2-D PAGE, developed at the University Hospital of Geneva, is such a third-generation software system for 2-DE analysis. Based on unique image processing algorithms, this user-friendly object-oriented software package runs on multiple platforms, including Unix, MS-Windows 95 and NT, and Power Macintosh. It provides efficient spot detection and quantitation, state-of-the-art image comparison, statistical data analysis facilities, and is Internet-ready. Linked to proteome databases such as those available on the World Wide Web, it represents a valuable tool for the "Virtual Lab" of the post-genome area.

Algorithms↗
PubMed1985

Quantitative EEG and neuropsychological effects of piracetam and of the association piracetam-lecithin in healthy volunteers.

The electroencephalographic (EEG) and neuropsychological effects of single, oral doses or piracetam (800-6,400 mg) and of its association with lecithin (4,800 mg and 25 g, respectively) were investigated in two groups of healthy volunteers in placebo-controlled studies. The EEG was quantified by power spectral analysis; both parametric and nonparametric procedures were applied to process the EEG and neuropsychological data statistically. The drug plasma concentration was assessed (gas chromatography) in concomitance with the EEG and neuropsychological measurements. Piracetam was found to elicit systematic EEG effects, namely a decrease in the low-frequency components and an increase in the power of the 8.5- to 12.0-Hz and of the fast-frequency components. The EEG modifications were restricted to the anterior scalp areas; its detection by means of parametric statistics was conditioned by the relevant individual variability and was inferred resting upon a number of criteria (indication at nonparametric tests, topography, consistency across subjects, replicability, etc). The correlation between EEG changes and drug plasma concentration was ambiguous, and the compound was not found to be effective on any of the neuropsychological variables considered. The study exemplifies some of the methodological problems in quantitative pharmaco-EEG and emphasizes the relevance of topography and replication.

Brain↗
PubMed1993

Statistical analysis of in vivo tumor growth experiments.

We review and compare statistical methods for the analysis of in vivo tumor growth experiments. The methods most commonly used are deficient in that they have either low power or misleading type I error rates. We propose a set of multivariate statistical modeling methods that correct these problems, illustrating their application with data from a study of the effect of alpha-difluoromethylornithine on growth of the BT-20 human breast tumor in nude mice. All the methods find significant differences between the alpha-difluoromethylornithine dose groups, but recommended sample sizes for a subsequent study are much smaller with the multivariate methods. We conclude that the multivariate methods are preferable and present guidelines for their use.

Animals↗
PubMed1992

The analysis of regional patterns in health data. II. The power to detect environmental effects.

Three measures of spatial clustering (Moran's I, Geary's c, and a rank adjacency statistic, D) were evaluated for their power to detect regional patterns in health data. The patterns represented various environmental effects: a latitude gradient; residence near a contaminated water supply; disease "hot spots"; relation to socioeconomic status and urbanization; and general spatial autocorrelation. While the methods had high power to detect certain patterns, they were also affected by factors such as the shape of the map, its regional structure, and the spatial distribution of explanatory variables. The power was sometimes low, even for strong geographic trends, particularly for D. Moran's I had the highest power most often. We conclude that use of these methods requires careful specification of the anticipated geographic pattern and awareness of idiosyncratic effects in the study of particular maps.

Bias↗
PubMed1984

Aortic and renal vascular disease. Factors affecting the value of combined procedures.

Assessment of the predictive value of preoperative factors in the determination of operative risk in 50 patients who underwent simultaneous aortic and renovascular procedures over a 10-year period is reported. There were six operative mortalities (12%). Factors associated with increased mortal risk were azotemia (43% vs. 7%), associated complex renal or visceral procedures (31% vs. 5%), treatment of aortic aneurysm vs. occlusive disease (17% vs. 5%), positive EKG (19% vs. 4%), age over 60 years (20% vs. 4%), and a history of diffuse peripheral vascular disease (18% vs. 7%). None of these differences, by themselves, had statistical significance. Through discriminate analysis with assignment of weighted scores to the five most powerful predictors of operative death (complex procedure--4, azotemia--4, aortic aneurysm repair--3, positive electrocardiogram--2, history of diffuse vascular disease--2), a weighted score of greater than or equal to 10 predicted operative death with an 83% sensitivity and 93% specificity (p = 0.003). Although advanced age, diabetes, severity of hypertension, and history of heart disease were associated with increased operative risk, they contributed minimal discriminate value to that provided by the preceding five variables. This was because these weaker risk factors were usually found in association with the predictors in the discriminant score. This study suggests that in patients with high weighted discriminant scores (greater than or equal to 10), consideration of operative risk is particularly important in evaluation of the proposed value of combined procedures.

Adult↗
PubMed2002

Computational method for reducing variance with Affymetrix microarrays.

BACKGROUND: Affymetrix microarrays are used by many laboratories to generate gene expression profiles. Generally, only large differences (> 1.7-fold) between conditions have been reported. Computational methods to reduce inter-array variability might be of value when attempting to detect smaller differences. We examined whether inter-array variability could be reduced by using data based on the Affymetrix algorithm for pairwise comparisons between arrays (ratio method) rather than data based on the algorithm for analysis of individual arrays (signal method). Six HG-U95A arrays that probed mRNA from young (21-31 yr old) human muscle were compared with six arrays that probed mRNA from older (62-77 yr old) muscle. RESULTS: Differences in mean expression levels of young and old subjects were small, rarely > 1.5-fold. The mean within-group coefficient of variation for 4629 mRNAs expressed in muscle was 20% according to the ratio method and 25% according to the signal method. The ratio method yielded more differences according to t-tests (124 vs. 98 differences at P < 0.01), rank sum tests (107 vs. 85 differences at P < 0.01), and the Significance Analysis of Microarrays method (124 vs. 56 differences with false detection rate < 20%; 20 vs. 0 differences with false detection rate < 5%). The ratio method also improved consistency between results of the initial scan and results of the antibody-enhanced scan. CONCLUSION: The ratio method reduces inter-array variance and thereby enhances statistical power.

Adult↗
PubMed2004

Predictors for severe cardiac complications after hematopoietic stem cell transplantation.

The value of pre-transplant factors for predicting the development of cardiac complications after transplantation has been inconsistent among studies. We analyzed the impact of pre-transplant factors on the incidence of severe cardiac complications in 164 hematopoietic stem cell transplant recipients. We identified eight patients (4.8%) who experienced grade III or IV cardiac complications according to the Bearman criteria. Seven died of cardiac causes a median of 3 days after the onset of cardiac complications. On univariate analysis, both the cumulative dose of anthracyclines and the use of anthracyclines within 60 days before transplantation affected the incidence of severe cardiac complications (P=0.0091 and 0.011). The dissociation of heart rate and body temperature, which reflects "relative tachycardia", was also associated with a higher incidence of cardiac complications (P=0.024). None of the variables obtained by electrocardiography or echocardiography were useful for predicting cardiac complications after transplantation, although the statistical power might not be sufficient to detect the usefulness of ejection fraction. On a multivariate analysis, the cumulative dose of anthracyclines was the only independent significant risk factor for severe cardiac complications. We conclude that the cumulative dose of anthracyclines is the most potent predictor of cardiac complications and the administration of anthracyclines should be avoided within two months before transplantation.

Adult↗
PubMed1983

Correlation between EEG changes indicative of sedation and subjective responses.

The central activity of ketotifen ( Zaditen ), a benzocycloheptathiophene derivative for use in the prophylaxis of asthma, was determined by quantitative pharmaco-EEG in 7 healthy volunteers in a single-blind trial. During the 1st week of the trial, placebo was given twice daily followed by ketotifen 1 mg twice daily for 3 weeks. Placebo was again given for a further week. 15-min resting EEGs were taken immediately before and 3 and 6 h after medication on 8 defined days during the study, and the subjects were asked for side effects. Lead O2-Cz was analyzed by spectral analysis, and the relative power of the delta, theta, and fast and slow alpha bands as well as the dominant alpha frequency were calculated. The mean of each of these parameters was calculated per subject for each of the three measurements on each study day and compared with the baseline by means of one-way analysis of variance. A statistically significant slowing of the dominant alpha frequency, a decrease of the relative power of the fast alpha activity, and an increase of the relative power of the theta rhythm were found. These effects, indicative of a mild sedation, were highest during the 1st week of treatment with ketotifen, with a peak at the 3rd day, and gradually decreased thereafter. In contrast to the sensitive pharmaco-EEG method, none of the subjects complained of sedation or tiredness while taking ketotifen.

Adult↗