Nonparametric Pattern Research Articles

An investigation of the price discovery role of futures markets: A dynamic time warping analysis of the United States corn markets

AbstractFutures markets are critical to price discovery and often dominate spot markets. We analyze the linkages between daily corn futures and spot prices in the United States using dynamic time warping. This nonparametric pattern recognition technique has several advantages over traditional time series methods. First, it can detect multiple changes in the lead‐lag associations between the two prices within short intervals; the duration with which one series leads or lags another is not assumed to be fixed. Second, the method can be applied to time series without regard to their stationarity properties. This greatly expands the scope of this method to accommodate a wide range of time series. Third, it lends itself well to studying small samples, which econometricians encounter routinely. Fourth, the results are presented intelligibly using intuitive visualizations. Our results show that futures markets are critical to price discovery; nevertheless, spot markets dominate futures markets intermittently. We discuss the results in detail, setting them in the proper context. [EconLit Citations: C14, C32, Q02, Q11].

On the linkages between energy and agricultural commodity prices: A dynamic time warping analysis

We use dynamic time warping, a non-parametric pattern recognition method, to study interlinkages between major energy and agricultural commodity prices. Cluster analysis is conducted to group commodity prices based on their behavioral likeness by maximizing the differences between groups while minimizing the differences within groups. Two clusters emerge: one comprises the prices of crude oil and six major agricultural commodities, whereas the other contains coal and natural gas prices. Regarding lead-lag associations, oil prices generally lag crop prices; however, there are periods during which the former lead the latter. Furthermore, the duration with which oil prices lead or lag crop prices changes frequently.

A two-state Markov chain model for slug flow in horizontal ducts

Intermittent flows are common flow patterns in gas–liquid horizontal flow and attract attention and great research effort due to its importance for industrial and engineering applications. The slug flow is typically modelled based on a unit cell varying from an elongated air bubble with a liquid film in segregated flow pattern and an aerated liquid plug, the slug region, with remarkable stochastic characteristics of its alternating regions. In this paper, a two-state Markov chain model is proposed to represent the stochastic dynamics of developed slug flow in horizontal pipes. Each state represents either the liquid slug or the elongated bubble regions and the transition probabilities dictate the change of the given discrete time measurement to stay at a given state or change. This simple but insightful description of the phenomenon allows an analytical treatment of the statistics of Markov chain stochastic process. Measurement stations with two double wire resistive sensors are used to obtain the void fraction time series and a corresponding two-state representation. Each state is classified by a threshold defined by an unsupervised and non-parametric pattern recognition approach. The state transition matrix is then estimated for each corresponding experimental point. Thus random samples can be synthetically regenerated with the same statistical features of the corresponding measurements. It is shown that the Markov chain model can successfully represent second-order statistics of the measurement, such as the autocorrelation and power spectral density, given an appropriate choice of the chain order. Moreover, a cross correlation-based time delay estimation is proposed for the two-sensor measurement station and additional information is obtained from the slug flow. Subsequently, statistics of some slug flow features are estimated using the proposed approach and their interpretation as random variables derived from the void fraction stochastic process is discussed.

0159 Sleep-wake stability and variability in the middle-aged adult population: a UK Biobank study

Abstract Introduction Given the increasing use of consumer, wrist-worn devices with triaxial accelerometry (actigraphy), understanding whether 24-hr activity patterns are associated with specific mental and physical health deficits is of paramount importance. The UK Biobank, a community-based sample of adults in the United Kingdom, provides an opportunity to examine this question given its size (more than 100,000 actigraphy records) and scope (association health records). As a first step in understanding these relationships, understanding the impact of missing data, ways to interpolate missing data, and the general characteristics of 24-hr patterns is necessary. Methods A subset (n=70) of complete (i.e., no missing data) actigraphy records from individuals participating in the UK Biobank were used to examine the impact of missing data on intradaily variability (IV; rhythm fragmentation) and interdaily stability (IS; rhythm regularity). Data were intentionally removed and imputed and the impact of the manipulations was examined with Bland-Altman statistics. After determining the best imputation method and the limits of the method, it was applied to missing data in the full cohort, resulting in 82,840 actigraphy records. These were examined for IV and IS, as well as relative amplitude and the timing of L5 and M10. Data were categorized by age, gender, ethnicity, BMI and material deprivation. ANOVA with eta² effect sizes were used for comparisons. Data shown as median (interquartile range). Results Relative to IV and IS, median and mean imputation methods corrected for missing data of up to 24 hours. Linear imputation of long (>3 hours) missing data worsened IV and IS scores. Non-parametric patterns in the general population were within expected range, with IV=0.89(0.74-1.05), IS=0.55(0.46-0.63), RA=0.90(0.85-0.99), L5-timing=00:52 (00:07-01:37), and M10-timing=08:25(07:40-09:20). Stratifying by gender, age, ethnicity, BMI and material deprivation resulted in significant differences within all groups (p<0.0001), but small effect sizes (0.0019-0.00052). Conclusion Median imputation is useful for correcting for missing data (<24 hours) when examining IV and IS. Non-parametric analysis of the general population indicated values within the expected range. Even though there were significant differences in non-parametric outcomes between genders, age groups, ethnicities, body-mass index and material deprivation, none of these had significant effect sizes. Support (If Any) This research has been conducted using the UK Biobank Resource

Application of a Nonparametric Pattern Recognition Algorithm to the Problem of Testing the Hypothesis of the Independence of Variables of Multi-Valued Functions

Application of a Nonparametric Pattern Recognition Algorithm to the Problem of Testing the Hypothesis of the Independence of Variables of Multi-Valued Functions

Information system of remote sensing data analysis

The information system is designed to solve the problems of analyzing remote sensing data and making decisions using non-parametric pattern recognition algorithms, the synthesis of which is based on kernel estimates of probability density. Initial information is compiled by training samples on the states of the investigated natural objects and their corresponding spectral data, which are presented in Microsoft Excel files. The application of the software provides the following functions: primary processing of remote sensing data to evaluate the main quantitative characteristics of the laws of distribution of random variables; testing of the hypothesis on distributions of multivariate random variables based on non-parametric pattern recognition algorithms; estimating the state of natural objects by spectral data; mapping of territories by state of natural objects based on spectral data of earth surface elements and their corresponding spatial coordinates. Results of the presented functional tasks are saved in the form of reports in graphic files and spreadsheets of Microsoft Excel. Software tools can be used in the study of various nature objects from remote sensing data.

Application of a nonparametric pattern recognition algorithm in the problem of testing the hypothesis about the independence of variables of ambiguous functions

Application of a nonparametric pattern recognition algorithm in the problem of testing the hypothesis about the independence of variables of ambiguous functions

Formation of Sets of Independent Components of a Multidimensional Random Variable Based on a Nonparametric Pattern Recognition Algorithm

Formation of Sets of Independent Components of a Multidimensional Random Variable Based on a Nonparametric Pattern Recognition Algorithm

A method of sequentially generating a set of components of a multidimensional random variable using a nonparametric pattern recognition algorithm

We study in which way a priori information on the independence of random variables affects the approximation accuracy of a nonparametric estimate of the Rosenblatt–Parzen probability density. A new technique for generating sets of independent components of a multidimensional random variable is proposed. The methodology is based on testing the hypotheses of the independence of combinations of the multidimensional random variable components using a two-alternative nonparametric kernel algorithm for pattern recognition corresponding to the maximum likelihood criterion. Classes correspond to the domains of definition of the probability densities of sets of independent and dependent components of the multidimensional random variable. Nonparametric statistics of the kernel type are used to estimate the probability densities. The choice of the bandwidths of the kernel estimates of the probability densities is made from the condition of the minimum root-mean-square criterion. The sequential procedure for generating a set of independent components begins with the analysis of paired combinations of components of a multidimensional random variable. For each pair of components, the probability of an error in recognizing classes corresponding to the assumptions of independence and dependence of the considered components is estimated. A pair of components with the maximum difference between these errors is determined. If the errors obtained do not differ significantly, then there are no independent components in the considered multivariate random variable. If there is a significant difference in the probability estimates of class recognition errors, a pair of independent components is established. These components are included in a three-component set of a multidimensional random variable. The analysis of their combinations is carried out in the same way, following the above-described procedure. The process of generating the set of independent components is stopped when no reliable difference occurs any more between the probabilities of errors in recognizing situations belonging to the accepted classes. In this case, the previous set of independent components is the desired result. In contrast to the traditional methodology based on the Pearson criterion, the proposed approach allows us to bypass a problem of the decomposition of the range of values of random variables into multidimensional intervals. The method of generating a set of independent components of a multidimensional random variable is illustrated by the results of the analysis of spectral features of remote sensing data of forest tracts using space imagery from the Landsat-8 satellite.

Nonparametric pattern recognition algorithm for testing a hypothesis of the independence of random variables

A new method for testing a hypothesis of the independence of multidimensional random variables is proposed. The technique under consideration is based on the use of a nonparametric pattern recognition algorithm that meets a maximum likelihood criterion. In contrast to the traditional formulation of the pattern recognition problem, there is no a priori training sample. The initial information is represented by statistical data, which are made up of the values of a multivariate random variable. The distribution laws of random variables in the classes are estimated according to the initial statistical data for the conditions of their dependence and independence. When selecting optimal bandwidths for nonparametric kernel-type probability density estimates, the minimum standard deviation is used as a criterion. Estimates of the probability of pattern recognition error in the classes are calculated. Based on the minimum value of the estimates of the probabilities of pattern recognition errors, a decision is made on the independence or dependence of the random variables. The technique developed is used in the spectral analysis of remote sensing data.

Effect of Pilates exercises on blood glucose, urinary problems, sexual symptoms, pain and anxiety in women with gestational diabetes mellitus

PurposeTo verify the impact of Pilates training on blood glucose, urinary problems, sexual symptoms, pain and anxiety in women with gestational diabetes mellitus (GDM).MethodsOverall, 25 pregnant women with GDM were randomly divided into an experimental and a control group. The participants allocated into the experimental group were submitted to 12 weeks of conventional treatment for GDM associated with supervised Pilates exercises. The control group were submitted to 12 weeks of conventional treatment, without the Pilates intervention. Fasting blood glucose was measured with a glucose monitor. Urinary symptoms were assessed by using the Short-Form International Consultation on Incontinence Questionnaire. For sexual function, the authors applied the Female Sexual Function Index. Maternal weight gain was obtained from the patients’ medical records. Pain was assessed by visual analogue scale and localized by nordic questionnaire. Owing to a non-parametric pattern of the data, values were expressed as median and interquartile range. Inferential analysis was performed with the Mann-Whitney U test (to assess between-group comparisons) and Wilcoxon test (to assess pre- and post-intervention comparisons).ResultsConsidering the baseline similarity of the groups regarding anthropometric and clinical variables, Pilates training improved fasting glucose, maternal weight gain, and urinary incontinence score as compared with the group submitted exclusively to conventional therapy (<i>p</i> < 0.05).ConclusionsThe results reinforce the beneficial effects of supervised Pilates training on reducing blood glucose, maternal weight gain, and urinary incontinence in pregnant women with GDM.

Formation of sets of independent components of a multidimensional random variable based on a nonparametric pattern recognition algorithm

The possibility of circumventing the problem of decomposition of the range of values of random variables when testing various hypotheses is considered. A brief review of the literature on this problem is given. A method for forming sets of independent components of a multidimensional random variable is proposed, based on hypotheses testing about the independence of paired combinations of components of a multidimensional random variable. The method uses a two-dimensional non-parametric algorithm for pattern recognition of the kernel type, corresponding to the criterion of maximum likelihood. In contrast to the traditional method based on the application of the Pearson criterion, the proposed approach avoids the problem of decomposing the range of values of random variables into multidimensional intervals. The results of computational experiments performed according to the method of forming sets of independent random variables are presented. Using the information obtained, an information graph is constructed, the vertices of which correspond to the components of a multidimensional random variable, and the edges determine their independence. Then the vertices of the complete subgraphs correspond to groups of independent components of a random variable. The obtained results form the basis for the synthesis of a multi-level nonparametric large volume data processing system, each level of which corresponds to a specific set of independent random variables.

Nonparametric “anti-Bayesian” quantile-based pattern classification

Parametric and nonparametric pattern recognition have been studied for almost a century based on a Bayesian paradigm, which is, in turn, founded on the principles of Bayes theorem. It is well known that the accuracy of the Bayes classifier cannot be exceeded. Typically, this reduces to comparing the testing sample to mean or median of the respective distributions. Recently, Oommen and his co-authors have presented a pioneering and non-intuitive paradigm, namely that of achieving the classification by comparing the testing sample with another descriptor, which could also be quite distant from the mean. This paradigm has been termed as being “anti-Bayesian,” and it essentially uses the quantiles of the distributions to achieve the pattern recognition. Such classifiers attain the optimal Bayesian accuracy for symmetric distributions even though they operate with a non-intuitive philosophy. While this paradigm has been applied in a number of domains (briefly explained in the body of this paper), its application for nonparametric domains has been limited. This paper explains, in detail, how such quantile-based classification can be extended to the nonparametric world, using both traditional and kernel-based strategies. The paper analyzes the methodology of such nonparametric schemes and their robustness. From a fundamental perspective, the paper utilizes the so-called large sample theory to derive strong asymptotic results that pertain to the equivalence between the parametric and nonparametric schemes for large samples. Apart from the new theoretical results, the paper also presents experimental results demonstrating their power. These results pertain to artificial data sets and also involve a real-life breast cancer data set obtained from the University Hospital Centre of Coimbra. The experimental results clearly confirm the power of the proposed “anti-Bayesian” procedure, especially when approached from a nonparametric perspective.

Parametrization of Survival Measures (Part II): Single Arm Studies

In some clinical applications in oncology randomized, double armed, and double-blind trials are not possible. In case of device applications, double-blinded conditions are nonrealistic, and with many times the randomization also has complications due to the high-line treatments where the reference cohort is not available; the active “arm” has mainly palliative initiative. Sometimes highly personalized therapies block the collection of the homogeneous group and limit its double-arm randomization. Our objective is to discuss the situations of the single arm evaluation and to give methods for the mining of information from this to increase the level of evidence of the measured dataset. The basic idea of the data-separation is the appropriate parameterization of the non-parametric Kaplan-Meier survival pattern by the poly-Weibull fit.

Methods for Rapid Selection of Kernel Function Blur Coefficients in a Nonparametric Pattern Recognition Algorithm

A fast algorithm is proposed for choosing the coefficients of blur coefficients for kernel functions in a nonparametric estimate of the separating surface equation for a two-alternative pattern recognition problem. The algorithm is based on the results of a study of the asymptotic properties of nonparametric estimates of the decision function in the recognition problem for patterns and the probability densities of the distribution of random variables in classes. We compare the proposed algorithm with the traditional approach based on minimizing the estimated probability of a classification error.

Matriz de risco como instrumento no planejamento de auditoria de obras públicas: uma proposta metodológica não-paramétrica

As matrizes de risco têm sido amplamente utilizadas como uma ferramenta de avaliação de risco em muitos campos devido à sua simplicidade e natureza intuitiva. Entretanto, a literatura especializada tem focado em suas aplicações nos mais diversos campos de atuação em vez de desenhá-las. Este trabalho tem por objetivo apresentar uma proposta metodológica robusta de matriz de risco para a seleção de contratos de obras públicas em amostras não-paramétricas. A metodologia é classificada quanto à origem como descritiva e quanto à abordagem do problema em quali-quantitativa, com padrão não-paramétrico com categorização das variáveis. O resultado demonstra a viabilidade da metodologia e a necessidade de melhorar os mecanismos de governança para um que priorize a análise de riscos no centro do planejamento para tomada de decisão dos gestores.

Method of fast algorithm bandwidth selection for kernel function in nonparametric pattern recognition algorithm

Method of fast algorithm bandwidth selection for kernel function in nonparametric pattern recognition algorithm

Research of efficiency of the statistical non-parametric pattern recognition models for forest land classification

The principles of the creation of pattern recognition models, based on using multispectral imagery of forest land, have been analyzed. The statistical non-parametric model has been suggested as a basic pattern recognition model and the probability density function - as a recognition feature. Efficiency of the different quality criteria has been discussed. The main directions for improving the pattern recognition models are regarded.

Nonparametric Algorithms for Estimating the States of Natural Objects

Modifications of a nonparametric pattern recognition algorithm corresponding to the maximum likelihood criterion with additional decision functions are considered. The synthesis of the proposed algorithms is based on the analysis of the ratios of the estimates of the probability density distributions of random variables in classes and their functionals with input thresholds. The choice of the thresholds is determined by specific features of the classification problem. The results obtained are applied for assessing the states of forest tracts on the basis of remote sensing data.

Using a multi-context design approach as manifestation of complexity: perceptions and experiences of students in design engineering

In recent years, awareness that design students need to be better equipped to deal with complexity has increased. The practical implications for design education are less evident. While students appreciate explicit methods and tools, we argue that they have to learn to work with ambiguity and interconnections as well. We performed research on the differences that advanced design students experience in terms of process and outcome when switching from self-chosen familiar tool-supported design methods to using a less familiar and less prescriptive multi-contextual approach. The latter represents our chosen manifestation of possible real-life complexity in design challenges. The reflections show a diversity of non-parametric patterns. In general, the intentional multi-context approach was appreciated for its positive effect on encouraging creativity and quality of the results. The reflections raise several points of attention when addressing the concept of complexity with design students in education curricula.