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1.
Rev. cuba. invest. bioméd ; 40(1): e822, ene.-mar. 2021. tab
Article in Spanish | CUMED, LILACS | ID: biblio-1289443

ABSTRACT

Introducción: El CrossFit ® es actualmente la modalidad de entrenamiento funcional de alta intensidad de mayor difusión. No obstante, no existen investigaciones que relacionen la velocidad aérobica máxima continua (VAM-C) e intermitente (VAM-I) con el rendimiento en este entrenamiento. Objetivo: Determinar la relación entre la velocidad aérobica máxima continua e intermitente con el rendimiento del CrossFit ® WOD Karen en sujetos físicamente activos. Métodos: Participaron 14 hombres y 6 mujeres, en tres días se realizaron las pruebas con un intervalo de 24-48 horas entre ellos, la velocidad aérobica máxima continua se evaluó a través del test de carrera 20 metros o Course Navette, la velocidad aérobica máxima intermitente se valoró por medio del 30-15 ITF (Intermittent Fitness Test) y por último se midió el rendimiento del WOD CrossFit ® Karen (150 lanzamientos de balón medicinal a pared en el menor tiempo posible). Los datos obtenidos fueron analizados en el paquete estadístico PSPP con un nivel de confianza del 95 por ciento y un p-valor del 0,05. Resultados: Los resultados obtenidos presentaron distribución normal (p > 0,05) para ambos sexos salvo el tiempo del WOD CrossFit ® Karen en hombres (p < 0,05). El coeficiente de correlación sugiere que la velocidad aérobica máxima continua obtuvo una relación grande (r = -0,61) en mujeres y moderada en hombres (r = -0,44), mientras que la velocidad aérobica máxima intermitente presentó una asociación muy grande en mujeres (r = -0,76) y hombres (r = -0,78), pero solamente significativo con la velocidad aérobica máxima intermitente en hombres (p < 0,01). Conclusión: Una mayor aptitud física aeróbica intermitente es más influyente en el rendimiento del CrossFit ® WOD Karen en sujetos físicamente activos(AU)


Introduction: CrossFit® is at present the most widely known high-intensity functional training exercise program. However, no studies are available describing the relationship of continuous maximal aerobic speed (MAS-C) and intermittent maximal aerobic speed (MAS-I) to performance in this training mode. Objective: Determine the relationship of continuous and intermittent maximal aerobic speed to CrossFit® WOD Karen performance in physically active subjects. Methods: Fourteen men and six women participated in the study. The tests were performed in three days with a 24-48 hours separation between them. Continuous maximal aerobic speed was evaluated with the 20-m shuttle run test or Course Navette test and intermittent maximal aerobic speed with the 30-15 ITF (Intermittent Fitness Test). Finally, performance of the CrossFit® WOD Karen program was assessed through 150 medicine ball throws to the wall in as little time as possible. The data obtained were analyzed with the PSPP statistical package, using a confidence level of 95 percent and a p-value of 0,05. Results: The results obtained show a normal distribution (p > 0,05) for both sexes, except for CrossFit® WOD Karen time in men (p < 0,05). The correlation coefficient suggests that continuous maximal aerobic speed exhibited a high association in women (r = -0,61) and a moderate association in men (r = -0,44), whereas intermittent maximum aerobic speed exhibited a very high association in women (r = -0,76) and men (r = -0,78), but was only significant with intermittent maximum aerobic speed in men (p < 0,01). Conclusion: A better intermittent aerobic physical aptitude is more influential on CrossFit® WOD Karen performance in physically active subjects(AU)


Subject(s)
Humans , Male , Female , Exercise , Normal Distribution , Physical Fitness , Athletic Performance/standards , Cardiorespiratory Fitness/physiology
2.
Journal of Biomedical Engineering ; (6): 512-519, 2021.
Article in Chinese | WPRIM | ID: wpr-888208

ABSTRACT

Vision is an important way for human beings to interact with the outside world and obtain information. In order to research human visual behavior under different conditions, this paper uses a Gaussian mixture-hidden Markov model (GMM-HMM) to model the scanpath, and proposes a new model optimization method, time-shifting segmentation (TSS). The TSS method can highlight the characteristics of the time dimension in the scanpath, improve the pattern recognition results, and enhance the stability of the model. In this paper, a linear discriminant analysis (LDA) method is used for multi-dimensional feature pattern recognition to evaluates the rationality and the accuracy of the proposed model. Four sets of comparative trials were carried out for the model evaluation. The first group applied the GMM-HMM to model the scanpath, and the average accuracy of the classification could reach 0.507, which is greater than the opportunity probability of three classification (0.333). The second set of trial applied TSS method, and the mean accuracy of classification was raised to 0.610. The third group combined GMM-HMM with TSS method, and the mean accuracy of classification reached 0.602, which was more stable than the second model. Finally, comparing the model analysis results with the saccade amplitude (SA) characteristics analysis results, the modeling analysis method is much better than the basic information analysis method. Via analyzing the characteristics of three types of tasks, the results show that the free viewing task have higher specificity value and a higher sensitivity to the cued object search task. In summary, the application of GMM-HMM model has a good performance in scanpath pattern recognition, and the introduction of TSS method can enhance the difference of scanpath characteristics. Especially for the recognition of the scanpath of search-type tasks, the model has better advantages. And it also provides a new solution for a single state eye movement sequence.


Subject(s)
Humans , Algorithms , Discriminant Analysis , Eye Movements , Markov Chains , Normal Distribution , Probability
3.
Journal of Peking University(Health Sciences) ; (6): 425-433, 2021.
Article in Chinese | WPRIM | ID: wpr-942197

ABSTRACT

Cryo-electron microscopy (cryo-EM) imaging has the unique potential to bridge the gap between cellular and molecular biology. Therefore, cryo-EM three-dimensional (3D) reconstruction has been rapidly developed in recent several years and applied widely in life science research to reveal the structures of large macromolecular assemblies and cellular complexes, which is critical to understanding their functions at all scales. Although the technical breakthrough in recent years, for example, the introduction of the direct detection device (DDD) camera and the development of cryo-EM software tools, made the three cryo-EM pioneers share the 2017 Nobel Prize, several bottleneck problems still exist that hamper the further increase of the resolution of single-particle reconstruction and hold back the application of in situ subnanometer structure determination by cryo-tomography. Radiation damage is still the key limiting factor in cryo-EM. In order to minimize the radiation damage and preserve as much resolution as possible, the imaging conditions of a low dose and weak contrast make cryo-EM images extremely noisy with very low signal-to-noise ratios (SNR), generally about 0.1. The high noise will obscure the fine details in cryo-EM images or reconstructed maps. Thus, a method to reduce the level of noise and improve the resolution has become an important issue. In this paper, we systematically reviewed and compared some robust filters in the cryo-EM field of two aspects, single-particle analysis (SPA) and cryo-electron tomography (cryo-ET), and especially studied their applications, such as, 3D reconstruction, visualization, structural analysis, and interpretation. Conventional approaches to noise reduction in cryo-EM imaging include the use of Gaussian, median, and bilateral filters, among other means. A Gaussian filter selects an appropriate filter kernel to conduct spatial convolution with a noisy image. Although noise with larger standard deviations in cryo-EM images can be suppressed and satisfactory performance is achieved in certain cases, this filter also blurs the images and over-smooths small-scale image features. This is especially detrimental when precise quantitative information needs to be extracted. Unlike a Gaussian filter, a median filter is based on the order statistics of the image and selects the median intensity in a window of the adjacent pixels to denoise the image. Although this filter is robust to outliers, it suffers from aliasing problems that possibly result in incorrect information for cryo-EM structure interpretation. A bilateral filter is a nonlinear filter that performs spatial weighted averaging and is more selective in the pixels allowing to contribute to the weighted sum, excluding the high frequency noise from the smoothing process. Thus, this filter can be used to smooth out noise while maintaining the edge details, which is similar to an anisotropic diffusion filter, and distinct from a Gaussian filter but its utility will be limited when the SNR of a cryo-EM image is very low. Generally, spatial filtering methods have the disadvantage of losing image resolution when reducing noise. A wavelet transform can exploit the wavelet's natural ability to separate a signal from noise at multiple image scales to allow for joint resolution in both the spatial and frequency domains, and thus has the potential to outperform existing methods. The modified wavelet shrinkage filter we developed can offer a remarkable improvement in image quality with a good compromise between detail preservation and noise smoothing. We expect that our review study on different filters can provide benefits to cryo-EM applications and the interpretation of biological structures.


Subject(s)
Algorithms , Cryoelectron Microscopy , Image Processing, Computer-Assisted , Normal Distribution , Signal-To-Noise Ratio , Tomography, X-Ray Computed
4.
Article in English | LILACS, BBO | ID: biblio-1101305

ABSTRACT

Abstract Objective: To evaluate the erosive potential of different alcoholic beverages according to pH, titratable acidity and buffering capacity. Material and Methods: Thirteen industrialized alcoholic beverages of different brands were selected and divided into five groups according to their type and composition. The pH measurement and titratable acidity for pH 5.5 and 7.0 were performed in triplicate in 50 mL of each beverage. The buffering capacity was calculated based on pH and titratable acidity for pH 7.0. ANOVA, Tukey, and Pearson correlation, with p<0.05, were used for data analysis. Results: Data showed normal distribution by Shapiro-Wilk test. The pH of alcoholic beverages ranged from 2.49 (Miks Ice Tea - Green Fruits) to 7.64 (Smirnoff). The highest values of acid titration (4.68) and buffer capacity (19.97) were observed in Smirnoff Ice. The following correlations (p<0.01) were noted between: pH and titratable acidity; buffering capacity and pH; buffering capacity and titratable acidity. Conclusion: Some beers and alcopops presented erosive potential due to their lower pH associated with high acid titration values. The whisky and sugarcane liquor examined were not potentially erosive.


Subject(s)
Tooth Erosion/etiology , Carbonated Beverages/adverse effects , Alcoholic Beverages/adverse effects , Acidity/adverse effects , Hydrogen-Ion Concentration , Beer , Brazil/epidemiology , Normal Distribution , Analysis of Variance , Statistics, Nonparametric , Saccharum
5.
Rev. Soc. Bras. Med. Trop ; 53: e20200331, 2020. tab, graf
Article in English | SES-SP, ColecionaSUS, LILACS | ID: biblio-1136846

ABSTRACT

Abstract INTRODUCTION: The acceleration of new cases is important for the characterization and comparison of epidemic curves. The objective of this study was to quantify the acceleration of daily confirmed cases and death curves using the polynomial interpolation method. METHODS: Covid-19 epidemic curves from Brazil, Germany, the United States, and Russia were obtained. We calculated the instantaneous acceleration of the curve using the first derivative of the representative polynomial. RESULTS: The acceleration for all curves was obtained. CONCLUSIONS: Incorporating acceleration into an analysis of the Covid-19 time series may enable a better understanding of the epidemiological situation.


Subject(s)
Humans , Pneumonia, Viral/epidemiology , Coronavirus Infections/epidemiology , Betacoronavirus , Pneumonia, Viral/mortality , United States/epidemiology , Brazil/epidemiology , Normal Distribution , Incidence , Russia/epidemiology , Coronavirus Infections , Coronavirus Infections/mortality , Pandemics , Data Analysis , Germany/epidemiology
6.
Journal of Biomedical Engineering ; (6): 1080-1088, 2020.
Article in Chinese | WPRIM | ID: wpr-879239

ABSTRACT

In clinic, intima and media thickness are the main indicators for evaluating the development of atherosclerosis. At present, these indicators are measured by professional doctors manually marking the boundaries of the inner and media on B-mode images, which is complicated, time-consuming and affected by many artificial factors. A grayscale threshold method based on Gaussian Mixture Model (GMM) clustering is therefore proposed to detect the intima and media thickness in carotid arteries from B-mode images in this paper. Firstly, the B-mode images are clustered based on the GMM, and the boundary between the intima and media of the vessel wall is then detected by the gray threshold method, and finally the thickness of the two is measured. Compared with the measurement technique using the gray threshold method directly, the clustering of B-mode images of carotid artery solves the problem of gray boundary blurring of inner and middle membrane, thereby improving the stability and detection accuracy of the gray threshold method. In the clinical trials of 120 healthy carotid arteries, means of 4 manual measurements obtained by two experts are used as reference values. Experimental results show that the normalized root mean square errors (NRMSEs) of the estimated intima and media thickness after GMM clustering were 0.104 7 ± 0.076 2 and 0.097 4 ± 0.068 3, respectively. Compared with the results of the direct gray threshold estimation, means of NRMSEs are reduced by 19.6% and 22.4%, respectively, which indicates that the proposed method has higher measurement accuracy. The standard deviations are reduced by 17.0% and 21.7%, respectively, which indicates that the proposed method has better stability. In summary, this method is helpful for early diagnosis and monitoring of vascular diseases, such as atherosclerosis.


Subject(s)
Carotid Arteries/diagnostic imaging , Carotid Intima-Media Thickness , Normal Distribution , Ultrasonography
7.
Journal of Biomedical Engineering ; (6): 765-774, 2020.
Article in Chinese | WPRIM | ID: wpr-879203

ABSTRACT

Heart sound segmentation is a key step before heart sound classification. It refers to the processing of the acquired heart sound signal that separates the cardiac cycle into systolic and diastolic, etc. To solve the accuracy limitation of heart sound segmentation without relying on electrocardiogram, an algorithm based on the duration hidden Markov model (DHMM) was proposed. Firstly, the heart sound samples were positionally labeled. Then autocorrelation estimation method was used to estimate cardiac cycle duration, and Gaussian mixture distribution was used to model the duration of sample-state. Next, the hidden Markov model (HMM) was optimized in the training set and the DHMM was established. Finally, the Viterbi algorithm was used to track back the state of heart sounds to obtain S


Subject(s)
Algorithms , Electrocardiography , Heart Sounds , Markov Chains , Normal Distribution
8.
Journal of Biomedical Engineering ; (6): 291-297, 2019.
Article in Chinese | WPRIM | ID: wpr-774208

ABSTRACT

Oral teeth image segmentation plays an important role in teeth orthodontic surgery and implant surgery. As the tooth roots are often surrounded by the alveolar, the molar's structure is complex and the inner pulp chamber usually exists in tooth, it is easy to over-segment or lead to inner edges in teeth segmentation process. In order to further improve the segmentation accuracy, a segmentation algorithm based on local Gaussian distribution fitting and edge detection is proposed to solve the above problems. This algorithm combines the local pixels' variance and mean values, which improves the algorithm's robustness by incorporating the gradient information. In the experiment, the root is segmented precisely in cone beam computed tomography (CBCT) teeth images. Segmentation results by the proposed algorithm are then compared with the classical algorithms' results. The comparison results show that the proposed method can distinguish the root and alveolar around the root. In addition, the split molars can be segmented accurately and there are no inner contours around the pulp chamber.


Subject(s)
Humans , Algorithms , Computers , Cone-Beam Computed Tomography , Image Processing, Computer-Assisted , Normal Distribution , Tooth , Diagnostic Imaging , Tooth Root , Diagnostic Imaging
9.
Journal of Rheumatic Diseases ; : 5-11, 2019.
Article in English | WPRIM | ID: wpr-719349

ABSTRACT

In data analysis, given that various statistical methods assume that the distribution of the population data is normal distribution, it is essential to check and test whether or not the data satisfy the normality requirement. Although the analytical methods vary depending on whether or not the normality is satisfied, inconsistent results might be obtained depending on the analysis method used. In many clinical research papers, the results are presented and interpreted without checking or testing normality. According to the central limit theorem, the distribution of the sample mean satisfies the normal distribution when the number of samples is above 30. However, in many clinical studies, due to cost and time restrictions during data collection, the number of samples is frequently lower than 30. In this case, a proper statistical analysis method is required to determine whether or not the normality is satisfied by performing a normality test. In this regard, this paper discusses the normality check, several methods of normality test, and several statistical analysis methods with or without normality checks.


Subject(s)
Data Collection , Methods , Normal Distribution , Statistics as Topic
10.
Korean Journal of Anesthesiology ; : 331-335, 2019.
Article in English | WPRIM | ID: wpr-759552

ABSTRACT

Most parametric tests start with the basic assumption on the distribution of populations. The conditions required to conduct the t-test include the measured values in ratio scale or interval scale, simple random extraction, normal distribution of data, appropriate sample size, and homogeneity of variance. The normality test is a kind of hypothesis test which has Type I and II errors, similar to the other hypothesis tests. It means that the sample size must influence the power of the normality test and its reliability. It is hard to find an established sample size for satisfying the power of the normality test. In the current article, the relationships between normality, power, and sample size were discussed. As the sample size decreased in the normality test, sufficient power was not guaranteed even with the same significance level. In the independent t-test, the change in power according to sample size and sample size ratio between groups was observed. When the sample size of one group was fixed and that of another group increased, power increased to some extent. However, it was not more efficient than increasing the sample sizes of both groups equally. To ensure the power in the normality test, sufficient sample size is required. The power is maximized when the sample size ratio between two groups is 1 : 1.


Subject(s)
Biostatistics , Normal Distribution , Sample Size
11.
rev. psicogente ; 21(40): 337-359, jul.-dic. 2018. tab
Article in Spanish | LILACS, COLNAL | ID: biblio-979577

ABSTRACT

Resumen Objetivo: El Índice de Satisfacción Sexual de Hudson constituye una medición unidimensional de la satisfacción sexual empleada en investigación y clínica. En México, se ha propuesto una forma reducida a 10 ítems del ISS (ISS-10), que ha servido de base a este estudio para aportar nuevas evidencias de validez cruzada (entre mujeres y hombres) y convergente; describir su distribución y estudiar su relación con seis variables sociodemográficas. Método: Se realizó una investigación instrumental en la que participaron 807 personas casadas o en unión libre de Monterrey, México, a las cuales se les aplicó el ISS-10, la Escala de Valoración de la Relación (RAS), la Escala de Engrandecimiento Marital (MAS) y otras cuatro escalas entre enero y mayo de 2014, mediante un muestreo de rutas aleatorias. Se aplicó análisis factorial confirmatorio multigrupo. Resultados: El modelo de un factor con 10 indicadores mostró invarianza entre mujeres y hombres, pero las puntuaciones del ISS-10 no siguieron una distribución normal. Además, en la muestra total, la correlación del ISS-10 con la satisfacción con la relación (RAS) fue muy alta (rS = .71) y con el engrandecimiento marital (MAS), alta (rS = .56). La edad, los años de casados o en unión libre y la escolaridad presentaron correlaciones bajas con el ISS-10 (rS de .13 a .27). El sexo y el estado civil fueron independientes del ISS-10. Conclusión: El Índice de Satisfacción Sexual, como una medición unidimensional de la satisfacción sexual reducida a 10 indicadores, presenta evidencias de validez; independientemente de que se aplique a hombre o mujer, y puede ser baremado a partir de puntuaciones de percentil.


Abstract Objective: Hudson's Index of Sexual Satisfaction is a one-dimensional sexual satisfaction measure, used for research and clinical practice. In Mexico, 10 items form (ISS-10) has been proposed. This research aims to provide new evidences related to cross-validity (among women and men) and convergent validity of ISS-10 form, describing distribution, and study and also its relationship with six socio-demographic variables. Method: An instrumental research was performed. ISS-10, Relationship Rating Scale (RAS), Marital Aggrandizement Scale (MAS) and three other scales were applied; 807 married or cohabiting people were randomly sampled from Monterrey, Mexico between January and May 2014. Multi-confirmatory factorial group analysis was applied for data analysis. Results: The factor model has 10 indicators that show invariance among women and men. ISS-10 scores did not follow a normal distribution. In the overall sample, ISS-10 correlated with relationship satisfaction (RAS) was very high (rS = .71), and with the marital aggrandizement (MAS) also was high (rS = .56). Age, years of marriage or cohabitation and years of schooling have low correlation with ISS-10 form (rS from .13 to .27). Sex and marital status were independent based on ISS-10. Conclusion: The Index of Sexual Satisfaction, considered as key-factor to measure sexual satisfaction was reduced to 10 indicators, showing that the validity of evidence, is independent of being male or female, and it can be scaled using percentile scores rank.


Subject(s)
Humans , Male , Female , Personal Satisfaction , Sex , Sexual Behavior , Orgasm , Normal Distribution , Demography , Factor Analysis, Statistical , Data Analysis , Mexico
12.
Journal of the Korean Association of Oral and Maxillofacial Surgeons ; : 25-28, 2018.
Article in English | WPRIM | ID: wpr-766305

ABSTRACT

OBJECTIVES: This study aimed to describe recent patterns in the types of statistical test used in original articles that were published in Journal of the Korean Association of Oral and Maxillofacial Surgeons. MATERIALS AND METHODS: Thirty-six original articles published in the Journal in 2015 and 2016 were ascertained. The type of statistical test was identified by one researcher. Descriptive statistics, such as frequency, rank, and proportion, were calculated. Graphical statistics, such as a histogram, were constructed to reveal the overall utilization pattern of statistical test types. RESULTS: Twenty-two types of statistical test were used. Statistical test type was not reported in four original articles and classified as unclear in 5%. The four most frequently used statistical tests constituted 47% of the total tests and these were the chi-square test, Student's t-test, Fisher's exact test, and Mann-Whitney test in descending order. Regression models, such as the Cox proportional hazard model and multiple logistic regression to adjust for potential confounding variables, were used in only 6% of the studies. Normality tests, including the Kolmogorov-Smirnov test, Levene test, Shapiro-Wilk test, and Scheffé's test, were used diversely but in only 10% of the studies. CONCLUSION: A total of 22 statistical tests were identified, with four tests occupying almost half of the results. Adoption of a nonparametric test is recommended when the status of normality is vague. Adjustment for confounding variables should be pursued using a multiple regression model when the number of potential confounding variables is numerous.


Subject(s)
Logistic Models , Methods , Normal Distribution , Oral and Maxillofacial Surgeons , Proportional Hazards Models
13.
Korean Journal of Anesthesiology ; : 144-156, 2017.
Article in English | WPRIM | ID: wpr-34198

ABSTRACT

According to the central limit theorem, the means of a random sample of size, n, from a population with mean, µ, and variance, σ², distribute normally with mean, µ, and variance, σ²/n. Using the central limit theorem, a variety of parametric tests have been developed under assumptions about the parameters that determine the population probability distribution. Compared to non-parametric tests, which do not require any assumptions about the population probability distribution, parametric tests produce more accurate and precise estimates with higher statistical powers. However, many medical researchers use parametric tests to present their data without knowledge of the contribution of the central limit theorem to the development of such tests. Thus, this review presents the basic concepts of the central limit theorem and its role in binomial distributions and the Student's t-test, and provides an example of the sampling distributions of small populations. A proof of the central limit theorem is also described with the mathematical concepts required for its near-complete understanding.


Subject(s)
Mathematical Concepts , Normal Distribution , Statistical Distributions
14.
Journal of Korean Medical Science ; : 1072-1076, 2017.
Article in English | WPRIM | ID: wpr-224179

ABSTRACT

Scientific journals are important scholarly forums for sharing research findings. Editors have important roles in safeguarding standards of scientific publication and should be familiar with correct presentation of results, among other core competencies. Editors do not have access to the raw data and should thus rely on clues in the submitted manuscripts. To identify probable errors, they should look for inconsistencies in presented results. Common statistical problems that can be picked up by a knowledgeable manuscript editor are discussed in this article. Manuscripts should contain a detailed section on statistical analyses of the data. Numbers should be reported with appropriate precisions. Standard error of the mean (SEM) should not be reported as an index of data dispersion. Mean (standard deviation [SD]) and median (interquartile range [IQR]) should be used for description of normally and non-normally distributed data, respectively. If possible, it is better to report 95% confidence interval (CI) for statistics, at least for main outcome variables. And, P values should be presented, and interpreted with caution, if there is a hypothesis. To advance knowledge and skills of their members, associations of journal editors are better to develop training courses on basic statistics and research methodology for non-experts. This would in turn improve research reporting and safeguard the body of scientific evidence.


Subject(s)
Confidence Intervals , Editorial Policies , Journalism , Normal Distribution , Peer Review , Publications , Research Design , Research Report
15.
The Korean Journal of Pain ; : 243-249, 2017.
Article in English | WPRIM | ID: wpr-207167

ABSTRACT

Pain is subjective, while statistics related to pain research are objective. This review was written to help researchers involved in pain research make statistical decisions. The main issues are related with the level of scales that are often used in pain research, the choice of statistical methods between parametric or nonparametric statistics, and problems which arise from repeated measurements. In the field of pain research, parametric statistics used to be applied in an erroneous way. This is closely related with the scales of data and repeated measurements. The level of scales includes nominal, ordinal, interval, and ratio scales. The level of scales affects the choice of statistics between parametric or non-parametric methods. In the field of pain research, the most frequently used pain assessment scale is the ordinal scale, which would include the visual analogue scale (VAS). There used to be another view, however, which considered the VAS to be an interval or ratio scale, so that the usage of parametric statistics would be accepted practically in some cases. Repeated measurements of the same subjects always complicates statistics. It means that measurements inevitably have correlations between each other, and would preclude the application of one-way ANOVA in which independence between the measurements is necessary. Repeated measures of ANOVA (RMANOVA), however, would permit the comparison between the correlated measurements as long as the condition of sphericity assumption is satisfied. Conclusively, parametric statistical methods should be used only when the assumptions of parametric statistics, such as normality and sphericity, are established.


Subject(s)
Analysis of Variance , Biostatistics , Normal Distribution , Pain Measurement , Visual Analog Scale , Weights and Measures
16.
MedicalExpress (São Paulo, Online) ; 3(2)Mar.-Apr. 2016. tab, graf
Article in English | LILACS | ID: lil-779132

ABSTRACT

OBJECTIVE: A previous study suggested that the p-value of normality test applied to RR intervals is an index able to quantify Heart Rate Variability (HRV) through correlation of traditional time and frequency domain indices. We investigate the association between the p-value of normality test applied in RR intervals and symbolic analysis of HRV. METHOD: We evaluated 32 healthy women between 18 and 30 years old. RR intervals were used for HRV analysis and we performed symbolic analysis, where RR intervals are joined by symbols. Sets of three consecutive symbols (RR intervals) were grouped into four types of clusters, as follows: 1. Three equal symbols (zero variation); 2: two equal, one divergent symbol (one variation); 3. Three different symbols monotonically ascending or descending (two like variations); 4. Three different symbols, forming a peak or a trough (two unlike variations). Frequency of occurrence of each type of cluster was calculated. Normality tests were applied to all RR intervals and the p-value was calculated. We computed the correlations between the p-value of normality test and symbolic analysis of HRV. RESULTS: Correlation coefficients between the p-value of normality test from Kolmorogov-Smirnov test and the four types of clusters showed no correlation for any of them. Likewise, the correlation coefficient index between the p-value of normality test calculated from the Shapiro-Wilk test and symbolic analysis produced no significant results for any of the four types of clusters. CONCLUSION: There was no significant correlation between the p-value of normality test and HRV symbolic analysis. The physiological significance of this result is that the PNT is not related to chaotic behavior of HRV.


OBJETIVO: Um estudo anterior sugeriu que o valor "p" do teste de normalidade (PNT) aplicado a intervalos RR é um índice capaz de quantificar variabilidade da frequência cardíaca através da correlação tradicional dos índices de tempo e frequência. Investigamos a associação entre o teste PNT aplicado a intervalos RR e a análise simbólica da variabilidade da frequência cardíaca. MÉTODO: Foram avaliadas 32 mulheres saudáveis entre 18 e 30 anos de idade. Os intervalos RR foram utilizados para análise da variabilidade da frequência cardíaca; foi realizada uma análise simbólica, onde intervalos RR são unidos por símbolos. Grupos de três símbolos consecutivos foram agrupados em quatro tipos de aglomerados, a saber: 1: três símbolos iguais (variação zero); 2: dois símbolos iguais, um divergente (uma variação); 3: três símbolos diferentes, monotonicamente crescentes ou decrescentes (duas variações iguais); 4: três símbolos diferentes, formando um pico ou uma calha (duas variações desiguais). Foi calculada a frequência de ocorrência de cada tipo de cluster. Testes de normalidade foram aplicados a todos os intervalos RR e o valor de "p" foi calculado. Calculamos as correlações entre o PNT e análise simbólica de HRV. RESULTADOS: Os coeficientes de correlação entre PNT de teste Kolmorogov-Smirnov e os quatro tipos de clusters não mostraram correlação com qualquer um deles. Da mesma forma, o coeficiente de correlação entre o índice PNT calculado a partir do teste de Shapiro-Wilk e a análise simbólica não produziu resultados significativos para qualquer dos quatro tipos de aglomerados. CONCLUSÃO: Não houve correlação significativa entre o PNT e análise simbólica da variabilidade da frequência cardíaca. O significado fisiológico deste resultado é que o PNT não está relacionado ao comportamento caótico da VFC.


Subject(s)
Humans , Female , Adult , Autonomic Nervous System/physiology , Cardiovascular System , Cardiovascular Physiological Phenomena , Normal Distribution , Heart Rate/physiology
17.
Braz. j. otorhinolaryngol. (Impr.) ; 81(1): 31-36, Jan-Feb/2015. tab, graf
Article in English | LILACS | ID: lil-741324

ABSTRACT

Introduction: The complexity of the nasal tip structures and the impact of surgical maneuvers make the prediction of the final outcome very difficult. Therefore, no single technique is enough to correct the several anatomical presentations, and adequate preoperative planning represents the basis of rhinoplasty. Objective: To present results of rhinoplasty, through the gradual surgical approach to nasal tip definition based on anatomical features, and to evaluate the degree of patient satisfaction after the surgical procedure. Methods: Longitudinal retrospective cohort study of the medical charts of 533 patients of both genders who underwent rhinoplasty from January of 2005 to January of 2012 was performed. Cases were allocated into seven groups: (1) no surgery on nasal tip; (2) interdomal breakup; (3) cephalic trim; (4) domal suture; (5) shield-shaped graft; (6) vertical dome division; (7) replacement of lower lateral cartilages. Results: Group 4 was the most prevalent. The satisfaction rate was 96% and revision surgery occurred in 4% of cases. Conclusion: The protocol used allowed the implementation of a gradual surgical approach to nasal tip definition with the nasal anatomical characteristics, high rate of patient satisfaction with the surgical outcome, and low rate of revision. .


Introdução: A complexidade das estruturas da ponta nasal e o impacto de manobras cirúrgicas sobre o seu suporte dificultam a previsão da forma final da mesma. Devido a isso, nenhuma técnica isolada é suficiente para corrigir adequadamente as numerosas apresentações anatômicas, sendo o planejamento pré-operatório, a base da rinoplastia. Objetivos: Apresentar resultados de rinoplastias, por meio da abordagem cirúrgica gradativa para definição da ponta nasal baseada nas características anatômicas, e avaliar o grau de satisfação dos pacientes após a realização do procedimento cirúrgico. Método: Estudo em coorte histórica longitudinal no qual foram avaliados os prontuários de 533 pacientes de ambos os gêneros submetidos à rinoplastia no período de Janeiro de 2005 a Janeiro de 2012. Os pacientes foram divididos em sete grupos: (1) Nenhuma cirurgia na ponta nasal;( 2) Divulsão interdomal; (3) Ressecção cefálica; (4) Sutura domal; (5) Enxerto em escudo; (6) Divisão vertical dos domus; (7) Reconstrução das cartilagens alares maiores. Resultados: O grupo 4 foi o de maior prevalência. A taxa de satisfação foi de 96% e a revisão cirúrgica ocorreu em 4% dos casos. Conclusão: O protocolo utilizado permitiu a associação da abordagem cirúrgica gradativa para definição da ponta nasal com as características anatômicas nasais, alta taxa de satisfação como resultado cirúrgico e baixa taxa de revisão. .


Subject(s)
Adolescent , Adult , Aged , Child , Female , Humans , Male , Middle Aged , Young Adult , Rhinoplasty/methods , Longitudinal Studies , Normal Distribution , Nose/anatomy & histology , Patient Satisfaction , Statistics, Nonparametric , Treatment Outcome
18.
Korean Journal of Anesthesiology ; : 540-546, 2015.
Article in English | WPRIM | ID: wpr-153543

ABSTRACT

In statistic tests, the probability distribution of the statistics is important. When samples are drawn from population N (micro, sigma2) with a sample size of n, the distribution of the sample mean X should be a normal distribution N (micro, sigma2/n). Under the null hypothesis micro = micro0, the distribution of statistics z=X-micro0/sigma/radical(n) should be standardized as a normal distribution. When the variance of the population is not known, replacement with the sample variance s2 is possible. In this case, the statistics X-micro0/s/radical(n) follows a t distribution (n-1 degrees of freedom). An independent-group t test can be carried out for a comparison of means between two independent groups, with a paired t test for paired data. As the t test is a parametric test, samples should meet certain preconditions, such as normality, equal variances and independence.


Subject(s)
Biostatistics , Matched-Pair Analysis , Normal Distribution , Sample Size
19.
Journal of Biomedical Engineering ; (6): 197-201, 2015.
Article in English | WPRIM | ID: wpr-266701

ABSTRACT

Characteristics in pulse wave signals (PWSs) include the information of physiology and pathology of human cardiovascular system. Therefore, identification of characteristic points in PWSs plays a significant role in analyzing human cardiovascular system. Particularly, the characteristic points show personal dependent features and are easy to be affected. Acquiring a signal with high signal-to-noise ratio (SNR) and integrity is fundamentally important to precisely identify the characteristic points. Based on the mathematical morphology theory, we design a combined filter, which can effectively suppress the baseline drift and remove the high-frequency noise simultaneously, to preprocess the PWSs. Furthermore, the characteristic points of the preprocessed signal are extracted according to its position relations with the zero-crossing points of wavelet coefficients of the signal. In addition, the differential method is adopted to calibrate the position offset of characteristic points caused by the wavelet transform. We investigated four typical PWSs reconstructed by three Gaussian functions with tunable parameters. The numerical results suggested that the proposed method could identify the characteristic points of PWSs accurately.


Subject(s)
Humans , Algorithms , Heart Rate , Normal Distribution , Pulse Wave Analysis , Methods , Wavelet Analysis
20.
Rev. chil. anest ; 43(2): 116-121, oct.2014. graf, ilus
Article in Spanish | LILACS | ID: lil-780392
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