PubMed Health⌕ Search

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 667 records · Page 37Linked to original sources
PubMed2002

Ovarian function and regulation of the hypothalamic-pituitary-ovarian axis after tubal sterilization.

OBJECTIVE: To assess the effects of laparoscopic tubal sterilization with Hulka or Filshie clip on ovarian function and regulation of the hypothalamic-pituitary-ovarian axis. STUDY DESIGN: Hormonal changes were evaluated in 33 women undergoing sterilization with Hulka (n = 16) or Filshie clips (n = 17). All participants were healthy, with regular menstrual cycles. The levels of estradiol, follicle-stimulating hormone, luteinizing hormone, sex hormone binding globulin, prolactin, testosterone and androstenedione were measured in one cycle immediately before and 3 and 12 months after sterilization on cycle days 3-7 and 20-24. Repeated measures analysis of variance, paired t test and nonparametric Friedman two-way analysis of variance were used for statistical analysis. RESULTS: The follicular phase estradiol values increased after sterilization. The highest values were observed three months after the procedure (204.8 +/- 119.1 pmol/L vs. 170.3 +/- 111.7 pmol/L) (P = .0407). The values declined to the presterilization level by 12 months (150.3 +/- 71.3 pmol/L). The luteal phase estradiol values did not change significantly. No change in any of the other hormones studied took place, with the exception of a slight increase in follicular phase luteinizing hormone levels (4.4 +/- 1.4 U/L in the first cycle, 5.1 +/- 1.3 U/L in the second cycle and 5.2 +/- 1.8 U/L in the third cycle) (P = .0553). CONCLUSION: Laparoscopic tubal sterilization increases follicular phase estradiol levels, but the change seems to be only temporary.

Adult↗
PubMed2003

Impact of the changing health care environment on fieldwork education: perceptions of occupational therapy educators.

To investigate how clinical fieldwork educators and academic fieldwork coordinators view the impact of the changing health care environment on student fieldwork education, current practice, and future of the profession, a 48-item questionnaire assessing the influence of recent changes in the health care system on fieldwork education was sent to 125 occupational therapy fieldwork educators and coordinators (response rate 62.4%). Differences between fieldwork educators and coordinators were analyzed statistically using nonparametric methods. Alpha level was set at p < 0.01 for all statistical comparisons. Fieldwork educators and coordinators agreed productivity expectations, number of hours worked, and time spent in documentation have increased, while job security, time for continuing education, and quality of patient care under the current reimbursement system have decreased, but diverged on several other issues. Fieldwork educators believed reimbursement issues did not affect their ability to accept fieldwork students, whereas academic coordinators believed declining reimbursement had negatively affected fieldwork educators' ability to accept students. Factors thought to facilitate the fieldwork shortage included cost reductions, changes in reimbursement, and increased productivity demands on clinicians.

Allied Health Personnel↗
PubMed1998

Educational outcomes of an otitis media workshop for primary care providers in Latin America.

Otitis media is a prevalent condition that can be diagnosed and treated by primary care providers skilled in otoscopy. Previous analysis demonstrated that brief, intensive instruction at one site in rural Mexico improved the test scores of health care providers and changed long-term practices (Eavey R, et al. Otolaryngol Head Neck Surg 1993; 109:895-8). We wanted to confirm these test score findings at other sites. A didactic course on otitis media with a practical otoscopy workshop was conducted at six Mexican locations and in one Venezuelan city by an interdisciplinary group of physicians. The same coded test was given immediately before and after the course. The Wilcoxon test for significance of intrasubject performance before and after intervention was used as a nonparametric assessment. At all seven sites (n = 190 subjects), test scores demonstrated statistically significant improvement (range = p < 0.001 to p < 0.0001). We conclude that this educational method consistently improved short-term knowledge of otitis media and that further teaching efforts and a longer term practice-impact study are warranted.

Child↗
PubMed2002

A susceptibility locus for migraine with aura, on chromosome 4q24.

Migraine is a complex neurovascular disorder with substantial evidence supporting a genetic contribution. Prior attempts to localize susceptibility loci for common forms of migraine have not produced conclusive evidence of linkage or association. To date, no genomewide screen for migraine has been published. We report results from a genomewide screen of 50 multigenerational, clinically well-defined Finnish families showing intergenerational transmission of migraine with aura (MA). The families were screened using 350 polymorphic microsatellite markers, with an average intermarker distance of 11 cM. Significant evidence of linkage was found between the MA phenotype and marker D4S1647 on 4q24. Using parametric two-point linkage analysis and assuming a dominant mode of inheritance, we found for this marker a maximum LOD score of 4.20 under locus homogeneity (P=.000006) or locus heterogeneity (P=.000011). Multipoint parametric (HLOD = 4.45; P=.0000058) and nonparametric (NPL(all) = 3.43; P=.0007) analyses support linkage in this region. Statistically significant linkage was not observed in any other chromosomal region.

Chromosome Mapping↗
PubMed2000

A generalized nonparametric test for lattice-ordered means.

Treatment means in factorial experiments are lattice ordered when there is an increase in mean response as the level of any factor is increased while holding the other factors fixed. Such means occur naturally in many experiments. A nonparametric test for lattice-ordered means involving a Kendall-type statistic will be summarized for k-factor factorial experiments. Specifically, the form of the test statistic and variance under the null hypothesis will be presented. In addition, a normalized version of the test statistic will be discussed and applied to relevant data.

Anabolic Agents↗
PubMed2005

The effect of the renewal of calcium hydroxide paste on the apexification and periapical healing of teeth with incomplete root formation.

AIM: To evaluate the influence of renewing calcium hydroxide paste on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals. METHODOLOGY: Forty premolars from four 6-month-old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedströem files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of one premolar in each dog were left empty (group 4-control), and those of the other nine teeth in each animal were filled with a calcium hydroxide-propylene glycol paste. All teeth were restored with reinforced zinc oxide cement (IRM) or IRM and amalgam (group 4). The paste was renewed and the teeth restored again 1 week later. Then, the nine teeth in each animal were divided into three experimental groups: group 1 - paste not changed; group 2 - paste renewed every 4 weeks for 5 months; and group 3 - paste renewed after 3 months had elapsed. The teeth were restored with IRM and amalgam (groups 1 and 3) or IRM (group 2). The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate six parameters: apical calcified tissue barrier, inflammatory reaction, bone and root resorption, paste extrusion and microorganisms. Results of experimental groups were analysed by Kruskal-Wallis nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. RESULTS: Significant differences (P < 0.05) were found in relation to the presence of bone resorption and paste in the periradicular area, the formation of a calcified tissue barrier at the apex, and the intensity of the apical inflammatory reaction. Bone resorption was more evident in group 1 (medicament not changed), and the presence of paste in the periodontal tissues was more common in groups 2 and 3. Renewal of the paste reduced the intensity of the inflammatory reaction (groups 2 and 3), but the formation of apical calcified tissue was more noticeable in the teeth where the paste had not been renewed. CONCLUSIONS: Replacement of calcium hydroxide paste was not necessary for apexification to occur, however, it did reduce significantly the intensity of the inflammatory process. Monthly renewal of calcium hydroxide paste reduced significantly the occurrence of apexification.

Animals↗
PubMed2006

Postoperative sensitivity in Class I composite resin restorations in vivo.

PURPOSE: This study evaluated the postoperative sensitivity of posterior Class I composite resin restorations, restored with a self-etching or a total-etch one-bottle adhesive system. MATERIALS AND METHODS: One hundred four restorations were replaced by one clinician in 52 patients. Each patient received two restorations. After cavity preparations were completed under rubber-dam isolation, they were restored using Clearfil SE Bond or Single Bond and a resin-based restorative material (Filtek Z250). Sensitivity was evaluated at 0 and 7 days and 6 months using cold stimuli, and recorded using a visual analogue scale. If sensitivity was experienced on day 7, patients were also contacted on days 14 and 30 to assess the degree of sensitivity. The scores were analyzed as nonparametric data by means of the Friedman and Wilcoxon tests. RESULTS: No statistically significant differences in sensitivity were found between the two adhesives systems at days 0 and 7 or at 6 months. No spontaneous postoperative sensitivity was reported. CONCLUSIONS: The adhesives systems used in this study showed no differences in postoperative sensitivity, and did not show spontaneous sensitivity after 6 months.

Acrylic Resins↗
PubMed1997

Spatial statistical analysis of Chinese cancer mortality: a comparison study of the D statistic.

In this paper, we study a nonparametric spatial pattern test statistic, the D statistic. The D statistic is an effective test statistic for testing spatial patterns in regional health data. Comparison studies of the D statistic with fixed weights and random weights are illustrated on the atlas of the Chinese cancer mortality rates and on other cancer atlas. Some social, economic and environmental reasons for statistically significant spatial autocorrelations of the Chinese cancer mortality rates were given in the discussion section. The method for calculating the mean and the variance of the randomly weighted D statistic is given in the appendix.

China↗
PubMed1998

Comparison of treatment of tardive dystonia and idiopathic cervical dystonia with botulinum toxin type A.

To compare clinical parameters of patients treated with botulinum toxin type A (BTX) for treatment of idiopathic cervical dystonia (ICD) and for tardive cervical dystonia (TCD), we studied 156 patients (149 with ICD and 7 with TCD) who were treated with serial injections of BTX over 5 years. We hypothesized that patients with TCD and ICD would demonstrate similar improvement in severity scores after treatment with BTX. The diagnosis, dates, dosages, and frequency of BTX injected and severity assessments were recorded into a computerized database. Nonparametric Wilcoxon rank sum and signed-rank tests were used to assess statistical significance. The change in severity scores between the first treatment and last treatment in both groups was not statistically significant (p = 0.4859), indicating similar improvement. The difference in BTX doses was significant (p = 0.0045). ICD patients (n = 149) received an average of 219.8 +/- 63.5 units and those with TCD (n = 7) were treated with an average dose of 287.4 +/- 60.3 units. The average number of days between treatments for individuals with ICD was 142.9 +/- 85.8, similar to that for persons with TCD (144.7 +/- 64.5) (p = 0.6075). Our analysis provides preliminary evidence that the improvement from the administration of BTX for patients with ICD and TCD is similar.

Adult↗
PubMed2005

Temporal characteristics of feeding behavior in the Munich miniature pig.

UNLABELLED: Correlations between meal size and inter-meal intervals as a characteristic of ingestive behavior are generally calculated utilizing Pearson's correlation coefficient. However, this commonly used method may exhibit disadvantages and methodological problems when dealing with dependent time series. Alternatively, a modified version of Pearson's r (r(diff)) or a nonparametric procedure, Pfanzagl's T combined with an expanded sampling theorem offer a statistical alternative for correlational analysis, robust to stochastic interdependencies between time series. In two studies, porcine self-initiated feeding behavior was observed in a closed economy setup, and a comparison of all three correlation coefficients was performed. STUDY 1: Twelve Munich mini-pigs were observed for 2 weeks. The rate of food ingestion was a stable characteristic of each individual pig, feeding and defecation behavior were temporally associated and light/dark cycle differences were seen for feeding. STUDY 2: Eight Munich mini-pigs were studied for 4 weeks. Kendall's Tau was utilized to test the stability of feeding behavior across weeks. Stability increased over time and feeding was more stable during the light period. Both correlation measures revealed a strong association between meal size and inter-meal intervals. CONCLUSION: Munich-miniature pigs exhibited a stable pattern of self-initiated ingestive and excretory behaviors. In both studies, Pfanzagl's T-values as well as r(diff)-values revealed a corresponding and consistent association between meal size and inter-meal intervals. In combination with the conventional Pearson's r, all three coefficients characterize different aspects of feeding behavior.

Animals↗
PubMed2006

Detecting disease gene in DNA haplotype sequences by nonparametric dissimilarity test.

Association studies for complex diseases based on haplotype data have received increasing attention in the last few years. A commonly used nonparametric method, which takes haplotype structure into consideration, is to use the U-statistic to compare the similarities between genetic compositions in the case and control populations. Although the method and its variants are convenient to use in practice, there are some areas where the tests cannot detect even large differences between cases and controls. To overcome this problem and enhance the power, we propose a new form of the weighted U-statistic, which directly compares the dissimilarity between the haplotype structures in the case and control populations. We show that this test statistic is asymptotically a linear combination of the absolute values of normal random variables under the null hypothesis, and shifts strictly toward the right under the alternative, and therefore has no blind areas of detection. Simulation studies indicate that our test statistic overcomes the weakness of the existing ones and is robust and powerful as well.

Base Sequence↗
PubMed2003

The gamma-frailty Poisson model for the nonparametric estimation of panel count data.

In this article, we study nonparametric estimation of the mean function of a counting process with panel observations. We introduce the gamma frailty variable to account for the intracorrelation between the panel counts of the counting process and construct a maximum pseudo-likelihood estimate with the frailty variable. Three simulated examples are given to show that this estimation procedure, while preserving the robustness and simplicity of the computation, improves the efficiency of the nonparametric maximum pseudo-likelihood estimate studied in Wellner and Zhang (2000, Annals of Statistics 28, 779-814). A real example from a bladder tumor study is used to illustrate the method.

Algorithms↗
PubMed2004

Porosity of cpTi casting with four different casting machines.

STATEMENT OF PROBLEM: Porosity is a well-known problem in dental titanium casting, resulting in inferior mechanical properties of dental restorations. PURPOSE: The aim of this study was to evaluate the porosity of cpTi castings produced with different casting machines. MATERIAL AND METHODS: Four groups of 20 rectangular (30 x 3 x 0.5 mm) wax patterns were fabricated. Group CyII was cast in a CyclarcII casting machine, Group DAM in a Dor-A-Matic, Group TiF in a Titec 201F, and Group ETi in an EasyTi with cpTi, according to manufacturers' instructions. Groups CyII, DAM and TiF were invested with magnesia based Titavest CB and Group ETi with Ticoat S+L silica based investment. The percentage porosity of each specimen was determined using standardized digital radiographs and calculated by quantitative image analysis procedure. The results were statistically analyzed by nonparametric Kruskal-Wallis test (alpha=.05). RESULTS: No statistical differences were found among the groups tested; nevertheless, pore distribution among the specimens of the same group was inhomogeneous. The results show that the casting machines tested produced nonuniform porosity. CONCLUSIONS: Under the conditions of the present study, the type of casting machine does not significantly influence the internal porosity in cpTi castings.

Argon↗
PubMed2000

Reverse redistribution: revisited with myocardial contrast echocardiography.

The aim of this study is to better understand the pattern and nature of reverse redistribution (RR) in myocardial perfusion imaging. In 20 consecutive acute myocardial infarction (MI) patients, frequency of RR was correlated with that of subendocardial MI that was detected by myocardial contrast echocardiography (MCE). RR was judged to be present when there was more than one grade of worsening in perfusion on 24 hr delayed images compared with the initial rest images. MCE evaluated no opacification in the subendocardial myocardium to suggest subendocardial MI. Kendall's nonparametric correlation coefficiency was calculated. Concordant cases were 15 of 20 (75%) and correlation was statistically significant (p = 0.0285). Our results suggested that RR was correlated with MCE-detected nontransmural MI.

Adult↗
PubMed2001

Effectiveness of arm supports during typing for adults with neurological disorders.

Four computer-typing accommodations were evaluated to determine if arm supports would enhance typing performance and/or comfort of adults with neurological disorders. Each of 12 adults (6 females and 6 males) participated in 7-min typing tasks under the following conditions: 1) without arm support, 2) Ergo Rest arm support, 3) custom arm support in fixed mode, and 4) custom arm support with movable mode. The objective dependent variables were speed, errors, and type of errors. The subjective dependent measures were reported body part discomfort, and arm support ratings. The data were found to be nonparametric in nature. Therefore, nonparametric techniques were employed to analyze the data. Only one of the objective dependent measures were statistically significant; Type of error (additional key). This result may be attributed to the wide range of disability manifestations among participants. Subjective dependent measures were found to be statistically significant, leading to the conclusion that typing with an arm support was more comfortable and easier than without an arm support.

Adult↗