SEARCH · PubMed Health

Results for “Statistics, Nonparametric”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMedDate not supplied

Caregiver responses and needs. An ambulatory bone marrow transplant model.

PURPOSE: This longitudinal, descriptive outcomes study was conducted to compare the emotional responses and needs of the caregivers of patients who undergo bone marrow transplantation (BMT) for hematologic malignancies, as observed in an inpatient/outpatient (IPOP) setting with those in an inpatient setting. DESCRIPTION OF STUDY: A convenience sample of 43 caregivers for patients undergoing either autologous or allogeneic BMT was selected from both the inpatient unit (n = 26) and the IPOP ambulatory setting (n = 17). Emotional responses were measured by the Profile of Mood States. The importance and satisfaction of informational, patient-care, and psychological needs were assessed with the Caregiver Needs Survey, a modified version of the Home Cancer Caregiver Needs Survey. Data were collected at six points across the BMT trajectory, from before the procedure to 12 months after. Descriptive statistics were used to report sample characteristics, emotional responses, and needs. Nonparametric statistics were used to compare the IPOP and inpatient caregiver groups, and to identify relationships between emotional responses and needs within groups. RESULTS: IPOP caregivers were found to have significantly less mood disturbance at points before discharge. Both groups showed a decrease in mood disturbance 6 and 12 months after BMT. IPOP caregivers had higher levels of satisfaction of their informational and psychological needs at day 21. Significant correlations between total mood disturbance and satisfaction of informational, psychological, and patient-care needs were found for inpatient caregivers across treatment time points. CLINICAL IMPLICATIONS: These findings support the IPOP model of care as being less emotionally distressing for and better meeting the needs of family caregivers. Specific implications for practice include the importance of caregiver education in the area of patient-care information and of assessment and intervention to meet caregiver psychological needs. Continued evaluation of the impact of changes in care delivery on family caregivers is essential for the provision of comprehensive cancer care.

Activities of Daily Living↗

PubMed1999

Assessing research methodology training needs in emergency medicine.

OBJECTIVE: To determine the perceptions of emergency medicine (EM) academic faculty leaders and other academic emergency physicians regarding importance and knowledge of specific research methodology content areas and training priorities. METHODS: The authors conducted a confidential mail survey of 52 EM academic chairs, 112 residency directors, 116 research directors, and 400 randomly selected other members of the Society for Academic Emergency Medicine (SAEM). Respondents rated the importance of knowledge about each of 12 content areas for enhancing research productivity, rated their own knowledge of these areas, and identified training priorities. Standard descriptive statistics were used to characterize the study population; subgroup differences were examined by nonparametric statistics. RESULTS: 551 (81%) of those sampled returned surveys. Most (90%) respondents thought that knowledge about all selected content areas was important for enhancing research productivity; however, 7-37% (depending on the topic) reported little knowledge or experience in specific areas. Research directors reported highest overall knowledge levels (p < 0.001), followed by chairs, residency directors, and other SAEM members. Top training priorities (identified by all subgroups) included study planning (70%), problem identification/hypothesis construction (41%), and proposal writing (38%). CONCLUSIONS: These data support the continued need to offer broad training in research methodology, but suggest that greater emphasis be given to concepts involved in initiating and planning a study and to strengthening research proposal writing skills. These results should be of interest to academic departments who must address their own training needs, and help support the development of research methodology curricula on regional and national levels to advance the state of research in the specialty of EM.

Attitude of Health Personnel↗

PubMed1993

Use of eating-pattern messages to evaluate changes in eating behaviors in a worksite cholesterol education program.

OBJECTIVE: To determine whether eating-pattern messages can effectively be used in a worksite cholesterol education program to change eating behaviors. SUBJECTS: 91 randomly selected participants with initial serum cholesterol levels of 5.2 mmol/L attended the program. INTERVENTION: Eating-pattern messages were the focus of a successful 8-week worksite cholesterol education program conducted with city employees of Phoenix, Ariz. Participants completed self-administered questionnaires before and after the intervention that asked them to compare their current eating patterns with those addressed in the program. The majority (n = 84) of the participants attended five or more of eight available sessions, led by registered dietitians, which focused on the skills needed to decrease dietary fat. STATISTICAL ANALYSES PERFORMED: Parametric and nonparametric statistical tests were used to evaluate the direction and magnitude of changes in eating patterns. RESULTS: Participants made statistically significant changes in 11 of 15 eating patterns linked to messages delivered during the intervention. Changes in eating behaviors were related to improvements in blood lipid profiles. Results from a multiple regression analysis indicated that intervention-related changes in total cholesterol were significantly associated with combined eating-pattern message scores, and total cholesterol decreased 0.33 mmol/L for each unit decrease in the combined eating-pattern message score. APPLICATIONS/CONCLUSIONS: These findings indicate that eating-pattern messages can be used successfully to evaluate changes in fat-related eating behaviors.

Arizona↗

PubMed1994

Nutrition support team management of enterally fed patients in a community hospital is cost-beneficial.

OBJECTIVE: To determine whether nutrition support team (NST) management of enterally fed patients is cost-beneficial and to compare primary outcomes of care between team and nonteam management. DESIGN: A quasi-experimental study was conducted over a 7-month period. SETTING: A 400-bed community hospital. SUBJECTS: A convenience sample of 136 subjects who had received enteral nutrition support for at least 24 hours. Forty-two patients died; only their mortality data were used. Ninety-six patients completed the study. INTERVENTION: Outcomes, including cost, for enterally fed patients in two treatment groups--those managed by the nutrition support team and those managed by nonteam staff--were compared. MAIN OUTCOME MEASURES: Severity of illness level was determined for patients managed by the nutrition support team and those managed by nonteam staff. For each group, the following measures were adjusted to reflect a significant difference in average severity of illness and then compared: length of hospital stay, readmission rates, and mortality rates. Complication rates between the groups were also compared. The cost benefit was determined based on savings from the reduction in adjusted length of hospital stay. STATISTICAL ANALYSES PERFORMED: Parametric and nonparametric statistics were used to evaluate outcomes between the two groups. RESULTS: Differences were statistically significant for both severity of illness, which was at a higher level in the nutrition support team group (P < .001), and complication rate, which was greater in the nonteam group (P < .001). In the nutrition support team-managed group, there was a 23% reduction in adjusted mortality rate, an 11.6% reduction in the adjusted length of hospital stay, and a 43% reduction in adjusted readmission rate. Cost-benefit analysis revealed that for every $1 invested in nutrition support team management, a benefit of $4.20 was realized. APPLICATIONS: Financial and humanitarian benefits are associated with nutrition support team management of enterally fed hospitalized patients.

Aged↗

PubMed1999

A nonparametric method for the segmentation of the EEG.

A new method for segmentation of the EEG, based on a nonparametric statistical analysis, is proposed. A nonparametric approach was chosen because it minimises the need for a priori information about a signal. The method provides detection of change-points (quasi-stationary segments' boundaries) in almost any EEG characteristic for a given level of false alarm probability. The method was applied to 8-channels spontaneous EEG recordings obtained from 12 subjects in eyes closed and eyes open conditions to detect rapid fluctuations of the alpha rhythm power. After preliminary adjustment of false alarm probability values all the recordings were analysed in unsupervised regime with the same parameters. From 15 to 119 change-points were found per minute and EEG channel. Automatically detected change-points were in good correspondence with visual estimation of the instants of change in alpha activity.

Algorithms↗

PubMed2004

Quantitative evaluation of a pulmonary contour segmentation algorithm in X-ray computed tomography images.

RATIONALE AND OBJECTIVES: Pulmonary contour extraction from thoracic x-ray computed tomography images is a mandatory preprocessing step in many automated or semiautomated analysis tasks. This study was conducted to quantitatively assess the performance of a method for pulmonary contour extraction and region identification. MATERIALS AND METHODS: The automatically extracted contours were statistically compared with manually drawn pulmonary contours detected by six radiologists on a set of 30 images. Exploratory data analysis, nonparametric statistical tests, and multivariate analysis were used, on the data obtained using several figures of merit, to perform a study of the interobserver variability among the six radiologists and the contour extraction method. The intraobserver variability of two human observers was also studied. RESULTS: In addition to a strong consistency among all of the quality indexes used, a wider interobserver variability was found among the radiologists than the variability of the contour extraction method when compared with each radiologist. The extraction method exhibits a similar behavior (as a pulmonary contour detector), to the six radiologists, for the used image set. CONCLUSION: As an overall result of the application of this evaluation methodology, the consistency and accuracy of the contour extraction method was confirmed to be adequate for most of the quantitative requirements of radiologists. This evaluation methodology could be applied to other scenarios.

Algorithms↗

PubMed2005

Failure property distributions for conventional and highly crosslinked ultrahigh molecular weight polyethylenes.

To make stochastic (probabilistic) failure predictions of a conventional or highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) material, not only must a failure criterion be defined, but it is also necessary to specify a probability distribution of the failure strength. This study sought to evaluate both parametric and nonparametric statistical approaches to describing the failure properties of UHMWPE, based on the Normal and Weibull model distributions, respectively. Because fatigue and fracture properties of materials have historically been well described with the use of Weibull statistics, it was expected that a nonparametric approach would provide a better fit of the failure distributions than the parametric approach. The ultimate true stress, true strain, and ultimate chain stretch data at failure were analyzed from 60 tensile tests conducted previously. The ultimate load and ultimate displacement from 121 small punch tests conducted previously were also analyzed. It was found that both Normal and Weibull models provide a reasonable description of the central tendency of the failure distribution. The principal difference between the Normal and Weibull models can be appreciated in the predicted lower-bound response at the tail end of the distribution. The data support the use of both parametric and nonparametric methods to bracket the lower-bound failure prediction in order to simulate the failure threshold for UHMWPE.

Gamma Rays↗

PubMed2006

Evaluation of cancer-preventive activity and structure-activity relationships of 3-demethylubiquinone Q2, isolated from the ascidian Aplidium glabrum, and its synthetic analogs.

PURPOSE: 3-Demethylubiquinone Q2 was isolated from the ascidian Aplidium glabrum. The cancer-preventive properties and the structure-activity relationship for 3-demethylubiquinone Q2 and 12 of its synthetic analogs are reported. METHODS: Compounds, having one or several di- or triprenyl substitutions and quinone moieties with methoxyls in different positions, were synthesized. The cancer-preventive properties of compounds and were tested in JB6 Cl41 mouse skin cells, using a variety of assessments, including the methanethiosulfonate (MTS) assay, flow cytometry, and soft agar assay. Statistical nonparametric methods were used to confirm statistical significance. RESULTS: All quinones tested were shown to inhibit JB6 Cl41 cell transformation, to induce apoptosis, AP-1, and NF-kappaB activity, and to inhibit p53 activity. The most promising effects were indicated for compounds containing two isoprene units in a side chain and a methoxyl group at the para-position to a polyprenyl substitution. CONCLUSIONS: Quinones and demonstrated cancer-preventive activity in JB6 Cl41 cells, which may be attributed to the induction of p53-independent apoptosis. These activities depended on the length of side chains and on the positions of the methoxyl groups in the quinone part of the molecule.

Animals↗

PubMed1982

Orientation-specific visual evoked potential deficits in multiple sclerosis.

Checkerboard pattern reversal visual evoked potentials (VEPs) have proved useful in the confirmation of optic nerve disease in patients with multiple sclerosis (MS). Recently evidence of orientation-specific loss in contrast sensitivity and the presence of orientation-specific visual evoked potential (VEP) deficits in MS patients has been obtained using sinusoidal gratings as stimuli. This study reports the presence of orientation-specific VEP delay in MS using the conventional checkerboard pattern presented in two orientations: normally oriented (check condition) or diagonally oriented (diamond condition). Peak latency values of the N70 and P100 components of the VEP were statistically analyzed using appropriate ANOVA and nonparametric statistics. As a group of MS patients showed significant VEP delays under check and diamond pattern conditions. However, individual subject analysis revealed that about 20% of the MS population show VEP delay to only one pattern orientation. It was shown that by including a diamond pattern condition the diagnostic yield of VEP delay in these clinically definite MS patients was increased 11% over that obtained with check stimulation alone.

Electroretinography↗

PubMed2004

Radiation-induced histopathologic changes of the breast: the effects of time.

The increasingly frequent use of radiation therapy (RT) and systemic chemotherapy (CT) in the treatment of breast carcinoma requires surgical pathologists and cytologists to be familiar with the variable histologic changes initiated by these agents. Both treatment modalities can cause severe epithelial abnormalities, which are difficult to distinguish from carcinoma. The progression or regression of these histologic abnormalities in nonneoplastic breast tissue have not been extensively evaluated. Our study used 120 post-RT biopsy or mastectomy specimens from 117 patients (3 had bilateral carcinoma treated with RT) yielding 120 specimens. The interval from post-RT to biopsy or mastectomy ranged from 1 to 229 months with 25 of the specimens obtained 1 to 12 months after cessation of RT and 95 more than a year post-RT. Twenty-seven specimens were from >6 years after RT. The histologic features of pretreatment and posttreatment specimens were graded (0-3) blindly for each histologic feature to include stromal vascular and fibroblastic changes and epithelial cell changes of the terminal duct lobular unit and extralobular ducts as well as terminal duct lobular unit fibrosis/atrophy. The changes between the pre- and post-RT grades were all statistically significant (P < 0.05) using multiple nonparametric statistical methods and the parametric Student t test. The specimens obtained within the first year post-RT were compared with those from >1 year post-RT, >3 years post-RT, and >6 years post-RT. None of the histologic features evaluated showed significant changes over the various time intervals regardless of the statistical method used. The absence of regression of the radiation-induced histologic changes over time mandates the surgical pathologist be alert to the possibility of RT or CT even without that therapeutic history.

Abnormalities, Radiation-Induced↗

PubMed2002

Reference ranges of the dilute tissue thromboplastin inhibition and dilute Russell's viper venom tests revisited.

Reference ranges for two well-recognized tests for the lupus anticoagulant were determined utilizing 98 healthy subjects. The purpose of the study was to compare the reference ranges for the dilute tissue thromboplastin inhibition test on this group of healthy subjects calculated by parametric and nonparametric statistical methods, and to compare these results with results obtained on subsets of 20 and 40 randomly selected individuals from the group of 98. The same procedures were followed for the dilute Russell's viper venom test. Results were recorded in seconds of clotting times and in ratios (subject/mean of that set or subset). Statistical analysis revealed Gaussian distribution of the results in the large group as well as in each subset for both tests. The results showed more variation between sets of the dilute tissue thromboplastin inhibition test than of the dilute Russell's viper venom test. Nonparametrically calculated reference ranges were wider than those determined by a parametric method, especially if confidence intervals are provided for both reference ranges in the group of 94 controls or in a subset of 40 subjects. The nonparametric technique utilizes all data for the calculation of reference ranges of such sample sizes no matter how wide the results are spread. There was no significant difference between the reference ranges of subsets and the whole group (p > 0.05) calculated by both statistical techniques.

Adolescent↗

PubMed1997

[Statistical methods applied in retrospective risk assessment of endometrial adenocarcinoma occurrence].

A retrospective study about frequency of occurrence of endometrial adenocarcinoma in postmenopausal women which are associated with diabetes mellitus, overweight and hypertension was performed. The aim of the study was to have risk factors for carcinoma of endometrium estimated. The nonparametric statistics such as: 2 x 2 table chi 2/Phi2 test, observed versus expected chi 2 test and estimation of relative risk were applicable. A retrospective study (from 1991 to 1993) of 2887 patients of Institute of Obstetrics and Gynecology University School of Poznań with pathological sign and symptoms was performed.

Adenocarcinoma↗

PubMed1999

Inhibition of neutrophil derived lysosomal enzymes and reactive oxygen species by a novel tetrapeptide.

OBJECTIVE AND DESIGN: The role of a tetrapeptide derivative PEP 1261 {Boc-Lys(Boc)-Arg-Asp-Ser(tBu)-OtBu}, corresponding to residues 39-42 of human lactoferrin, has been tested in vitro in the modulation of neutrophil function. MATERIAL AND SUBJECTS: The level of non-enzymatic mediators of inflammation such as reactive oxygen species (ROS), enzymatic mediators such as myeloperoxidase (MPO) and lysosomal enzymes have been assessed in the presence or absence of PEP 1261 in phorbol 12-myristate 13 acetate (PMA) stimulated human neutrophils (n = 6) and also in neutrophils isolated from adjuvant induced arthritic rats (AIA) (n = 4). TREATMENT: PEP 1261, at a concentration of 0.14 mM, was added to the neutrophil cultures. STATISTICAL METHOD: The results were analysed by nonparametric statistics using Mann Whitney U test. RESULTS: Addition of PEP 1261 effectively blocked the H2O2 and O2*- release, decreased the levels of MPO levels (p< 0.01) and lysosomal enzymes (p < 0.05) as compared to PMA stimulated human neutrophils. PEP 1261 was also observed to inhibit the levels of H2O2, O2*-, MPO and lysosomal enzymes (p < 0.05) as compared to PMA stimulated control rat neutrophils and neutrophils from arthritic rats. CONCLUSIONS: The results of this study indicate that PEP 1261 could serve as an excellent antiinflammatory agent.

Acid Phosphatase↗

PubMed2000

EKG abnormalities during partial seizures in refractory epilepsy.

PURPOSE: This study assessed the frequency and character of ictal cardiac rhythm and conduction abnormalities in intractable epilepsy. Sudden unexpected death in epilepsy (SUDEP) is a major cause of excess mortality in people with refractory epilepsy, and cardiac arrhythmias during seizures may be responsible. The frequency of cardiac abnormalities during seizures in patients with refractory epilepsy must be determined. METHODS: Fifty-one seizures in 43 patients with intractable partial epilepsy were analyzed prospectively from CCTV-EEG monitoring with one ECG channel. Arrhythmias, repolarization abnormalities, and PR and QTc intervals were determined for preictal (3 min), ictal, and postictal (3 min) periods for one or more seizures per patient. Parametric statistics were used for continuous variables, and nonparametric statistics were used for categoric variables. RESULTS: Of the patients, 39% had one or more abnormalities of rhythm and/or repolarization during or immediately after seizures. Abnormalities included asystole (one), atrial fibrillation (one), marked or moderate sinus arrhythmia (six), supraventricular tachycardia (one), atrial premature depolarizations (APDs; eight), ventricular premature depolarizations (VPDs; two), and bundle-branch block (three). Mean seizure duration was longer in patients with abnormalities than in those without (204 vs. 71 s; p < 0.001). Generalized tonic-clonic seizures were also associated with increased occurrence of ictal ECG abnormalities (p = 0.006) as compared with complex partial seizures. There were no clinically significant differences in mean preictal and ictal/postictal PR and QTc intervals. CONCLUSIONS: Cardiac rhythm and conduction abnormalities are common during seizures, particularly if they are prolonged or generalized, in intractable epilepsy. These abnormalities may contribute to SUDEP.

Adolescent↗

PubMed2001

Macrostructural EEG characterization based on nonparametric change point segmentation: application to sleep analysis.

In the present investigation a new methodology for macrostructural EEG characterization based on automatic segmentation has been applied to sleep analysis. A nonparametric statistical approach for EEG segmentation was chosen, because it minimizes the need for a priori information about a signal. The method provides the detection of change-points i.e. boundaries between quasi-stationary EEG segments based on the EEG characteristics within four fundamental frequency bands (delta, theta, alpha and beta). Polysomnographic data of 18 healthy subjects were analyzed. Our findings show that nonparametric change-point segmentation in combination with cluster analysis enables us to obtain a clear picture of the hierarchical macrostructural organization of sleep, which is impossible to deduce from the unsegmented EEG data. Analysis of correlations between classically defined sleep stages and piecewise stationary power step functions reveals that three basic patterns can be distinguished: SWS (stage III/stage IV), stage II and stage I/REM. In accordance with correlation analyses, cluster detection shows that the cyclic sleep patterns during the course of the night become clearly observable by implementation of only three classes. Since the described methodology is based on a minimum of a priori assumptions, it may be useful for the development of a new sleep classification standard, which goes beyond the established Rechtschaffen and Kales scheme.

Adult↗

PubMed2003

Functional neuroanatomy of learned helplessness.

In the experiments reported here, female subjects were presented with reasoning tasks that changed from solvable to unsolvable, evoking "learned helplessness" or "loss of control" reactions in some subjects. Significant differences in slow cortical potential (SCP) changes were found between emotionally highly and lowly reactive subjects (grouped according to responses in postexperimental questionnaires) when processing unsolvable tasks. Cortical LORETA of SCP topographies and subsequent statistical nonparametric mapping (SnPM; analysis indicate clear reduction of anterior cingulate activity only with emotionally highly reactive subjects. In these subjects a region of the brain that is indispensable for goal-directed handling of tasks was switched off, whereas regions that are primarily engaged in processing the task stimuli were even more active during loss of control, although not at a statistically significant level. According to the anterior cingulate monitors the conflicts among brain regions and issues calls for further processing to the PFC that then guides behavior toward a goal. Learned helplessness might then be seen a state in which the function of the anterior cingulate is no longer maintained, perhaps due to the inhibitory influence of the amygdala possibly mediated via the brainstem dopaminergic ventral tegmental area.

Adult↗

PubMed1999

A multiple locus analysis of the collaborative study on the genetics of alcoholism data set.

Parametric and nonparametric statistical methods have been applied to the alcohol dependence data set collected in the Collaborative Study on the Genetics of Alcoholism (COGA). Our nonparametric linkage analyses (NPL) were based on the S(all) statistic of GENEHUNTER [Kruglyak et al., 1996] and the improved NPL statistic of GENEHUNTER-PLUS [Kong and Cox, 1997]. Based on likely regions for alcohol susceptibility genes identified from our nonparametric analyses, we reanalyzed the data using several two-locus models. We used the TMLINK program [Lathrop and Ott, 1990] in the LINKAGE package for these parametric analyses.

Alcoholism↗

PubMed2003

Complications with using ratios for environmental data: comparing enantiomeric ratios (ERs) and enantiomer fractions (EFs).

Complications arise when ratios are used to present environmental data because ratios are an unbounded, multiplicative scale that can lead to asymmetrical (skewed) data distributions. Enantiomeric ratios (ERs), historically used in discussions of chiral signatures, often are published as mean ER+/-single-value standard deviation. Application of statistical summaries, such as the widely used sample mean and standard deviation, to skewed ratio data is misleading and often inappropriate. Comparison of statistically summarized ER and enantiomer fraction (EF) data (which are based on a bounded, additive scale) for a range of hypothetical values reveals substantial discrepancies when conversion between ER and EF formats is used. These discrepancies are largest when the ratio data are greater than one and have large variability, because the data are more skewed. In many cases, the use of fractions instead of ratios can help to minimize misrepresentation of environmental data, including chiral data. The use of nonparametric statistical summaries, e.g., median and percentiles, provides a more robust indicator of the typical value and spread for both ER and EF data.

Data Interpretation, Statistical↗