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  • 1.
    Abrahamsson, Linda
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Statistical models of breast cancer tumour growth for mammography screening data2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2.
    Ahmady Phoulady, Hady
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Brownian Motions and Scaling Limits of Random Trees2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 3.
    Alm, Sven Erick
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Approximation and Simulation of the Distributions of Scan Statistics for Poisson Processes in Higher Dimensions1998In: Extremes, Vol. 1, p. 111-126Article in journal (Refereed)
    Abstract [en]

    Given a Poisson process in two or three dimensions we are interested in the scan statistic, i.e. the largest number of points contained in a translate of a fixed scanning set restricted to lie inside a rectangular area.

    The distribution of the scan statistic is accurately approximated for rectangular scanning sets, using a technique that is also extended to higher dimensions.

    The accuracy of the approximation is checked through simulation.

  • 4.
    Alm, Sven Erick
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Monotonicity of the difference between median and mean of Gamma distributions and of a related Ramanujan sequence2002Report (Other academic)
  • 5.
    Alm, Sven Erick
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Monotonicity of the difference between median and mean of gamma distributions and of a related Ramanujan sequence2003In: Bernoulli, ISSN 1350-7265, Vol. 9, no 2, p. 351-371Article in journal (Refereed)
    Abstract [en]

    For $n\ge0$, let $\lambda_n$ be the median of the $\Gamma(n+1,1)$ distribution. We prove that the sequence $\{\alpha_n=\lambda_n-n\}$ decreases from $\log 2$ to $2/3$ as $n$ increases from 0 to $\infty$. The difference, $1-\alpha_n$, between the mean and the median thus increases from $1-\log 2$ to $1/3$.

    This result also proves the following conjecture by Chen \& Rubin about the Poisson distributions: Let $Y_{\mu}\sim\text{Poisson}(\mu)$, and \lambda_n$ be the largest $\mu$ such that $P(Y_{\mu}\le n)=1/2$, then $\lambda_n-n$ is decreasing in $n$.

    The sequence $\{\alpha_n\}$ is related to a sequence $\{\theta_n\}$, introduced by Ramanujan, which is known to be decreasing and of the form

    $\theta_n=\frac13+\frac4{135(n+k_n)}$, where $\frac2{21}<k_n\le\frac8{45}$. We also show that the sequence $\{k_n\}$ is decreasing.

  • 6.
    Alm, Sven Erick
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    On measures of average degree for lattices2003Report (Other scientific)
  • 7.
    Alm, Sven Erick
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    On Measures of Average Degree for Lattices2006In: Combinatorics, Probability and Computing, Vol. 15, no 4, p. 477-488Article in journal (Refereed)
    Abstract [en]

    The usual definition of average degree for a non-regular lattice has the disadvantage that it takes the same value for many lattices with clearly different connectivity. We introduce an alternative definition of average degree, which better separates different lattices.

    These measures are compared on a class of lattices and are analyzed using a Markov chain describing a random walk on the lattice. Using the new measure, we conjecture the order of both the critical probabilities for bond percolation and the connective constants for self-avoiding walks on these lattices.

  • 8.
    Alm, Sven Erick
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    On monoticity of some binomial probabilities2010Report (Other academic)
  • 9.
    Alm, Sven Erick
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Upper and Lower Bounds for the Connective Constants of Self-avoiding Walks on the Archimedean and Laves Lattices2005In: J. Phys. A: Math. Gen., no 38, p. 2055-2080Article in journal (Refereed)
  • 10.
    Alm, Sven Erick
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Janson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Analysis and Applied Mathematics.
    Linusson, Svante
    Correlations for Paths in Random Orientations of G(n, p) and G(n, m)2011In: Random structures & algorithms (Print), ISSN 1042-9832, E-ISSN 1098-2418, Vol. 39, no 4, p. 486-506Article in journal (Refereed)
    Abstract [en]

    We study random graphs, both G(n, p) and G(n, m), with random orientations on the edges. For three fixed distinct vertices s, a, b we study the correlation, in the combined probability space, of the events {a -> s} and {s -> b}. For G(n, p), we prove that there is a p(c) = 1/2 such that for a fixed p < p(c) the correlation is negative for large enough n and for p > p(c) the correlation is positive for large enough n. We conjecture that for a fixed n >= 27 the correlation changes sign three times for three critical values of p. For G(n, m) it is similarly proved that, with p = m/((n)(2)), there is a critical p(c) that is the solution to a certain equation and approximately equal to 0.7993. A lemma, which computes the probability of non existence of any l directed edges in G(n, m), is thought to be of independent interest. We present exact recursions to compute P(a -> s) and P(a -> s, s -> b). We also briefly discuss the corresponding question in the quenched version of the problem.

  • 11.
    Alm, Sven Erick
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Linusson, Svante
    A Counter-Intuitive Correlation in a Random Tournament2011In: Combinatorics, probability & computing, ISSN 0963-5483, E-ISSN 1469-2163, Vol. 20, no 1, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Consider a randomly oriented graph G = (V, E) and let a, s and b be three distinct vertices in V. We study the correlation between the events {a -> s} and {s -> b}. We show that, counter-intuitively, when G is the complete graph K-n, n >= 5, then the correlation is positive. (It is negative for n = 3 and zero for n = 4.) We briefly discuss and pose problems for the same question on other graphs.

  • 12.
    Alm, Sven Erick
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Parviainen, Robert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Bounds for the connective constant of the hexagonal lattice2004In: J.\ Phys. A: Math. Gen., Vol. 37, p. 549-Article in journal (Refereed)
    Abstract [en]

    We give improved bounds for the connective constant of the hexagonal lattice. The lower bound is found by using Kesten's method of irreducible bridges and by determining generating functions for bridges on one-dimensional lattices.

    The upper bound is obtained as the largest eigenvalue of a certain transfer matrix. Using a relation between the hexagonal and the $(3.12^2)$ lattices, we also give bounds for the connective constant of the latter lattice.

  • 13.
    Alm, Sven Erick
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Parviainen, Robert
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Bounds for the Connective Constant of the Hexagonal Lattice2003Report (Other scientific)
  • 14.
    Almesjö, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Regression modeling of cyclotron spare parts consumption2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 15. Alsmeyer, Gerold
    et al.
    Biggins, J. D.
    Meiners, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    The functional equation of the smoothing transform2012In: Annals of Probability, ISSN 0091-1798, E-ISSN 2168-894X, Vol. 40, no 5, p. 2069-2105Article in journal (Refereed)
    Abstract [en]

    Given a sequence T = (T-i)(i >= 1) of nonnegative random variables, a function f on the positive halfline can be transformed to E Pi(i >= 1) f (tT(i)). We study the fixed points of this transform within the class of decreasing functions. By exploiting the intimate relationship with general branching processes, a full description of the set of solutions is established without the moment conditions that figure in earlier studies. Since the class of functions under consideration contains all Laplace transforms of probability distributions on [0, infinity), the results provide the full description of the set of solutions to the fixed-point equation of the smoothing transform, X =(d) Sigma(i >= 1) TiXi, where =(d) denotes equality of the corresponding laws, and X-1, X-2, ... is a sequence of i.i.d. copies of X independent of T. Further, since left-continuous survival functions are covered as well, the results also apply to the fixed-point equation X =(d) inf{X-i/T-i:i >= 1, T-i > 0}. Moreover, we investigate the phenomenon of endogeny in the context of the smoothing transform and, thereby, solve an open problem posed by Aldous and Bandyopadhyay.

  • 16. Alsmeyer, Gerold
    et al.
    Meiners, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Fixed points of inhomogeneous smoothing transforms2012In: Journal of difference equations and applications (Print), ISSN 1023-6198, E-ISSN 1563-5120, Vol. 18, no 8, p. 1287-1304Article in journal (Refereed)
    Abstract [en]

    We consider the inhomogeneous version of the fixed-point equation of the smoothing transformation, that is, the equation X=C-d + Sigma(i >= 1) TiXi, where =(d) means equality in distribution, (C, T-1, T-2, . . .) is a given sequence of non-negative random variables and X-1, X-2, . . . is a sequence of i.i.d. copies of the non-negative random variable X independent of (C, T-1, T-2, . . .). In this situation, X (or, more precisely, the distribution of X) is said to be a fixed point of the (inhomogeneous) smoothing transform. In the present paper, we give a necessary and sufficient condition for the existence of a fixed point. Furthermore, we establish an explicit one-to-one correspondence with the solutions to the corresponding homogeneous equation with C = 0. Using this correspondence and the known theory on the homogeneous equation, we present a full characterization of the set of fixed points under mild assumptions.

  • 17.
    Amiri, Saeid
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    On the Resampling of the Unbalanced Ranked Set SampleManuscript (preprint) (Other academic)
    Abstract [en]

    This paper considers the bootstrap approach of the unbalanced Ranked Set Sampling (RSS) method. Herethe sequence bootstrap is used to shift the analysis of the unbalanced RSS method to an analysis ofthe balanced RSS sample, and balanced RSS is also discussed. Here the consequences of differentalgorithms for carrying out resampling are discussed. The pro­posed methods are studied using Monte Carloinvestigations. Furthermore, the theoretical approach is discussed.

  • 18.
    Amiri, Saeid
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    The Comparison of Entropies  using the Resampling MethodManuscript (preprint) (Other academic)
    Abstract [en]

    This paper discusses the bootstrap test of entropies. Since the comparison of entropies is of prime interestin applied fields, finding an appropriate way to carry out such a comparison is of the utmost importance. This paperpresents how resampling should be performed to obtain an accurate p-value. Although the test using a pair-wise bootstrapconfidence interval has already been dealt with in some works, here the bootstrap tests are studied because it may demand quite adifferent resampling algorithm compared with the confidence interval. Moreover, the multiple test is studied. The proposed testsappear to yield several appreciable advantages. The easy implementation and the power of the proposed test can be considered asadvantages. Here the entropy of discrete and continuous variables is studied. The proposed tests are examined using Monte Carloinvestigations, and also evaluated using various distributions.

  • 19.
    Amiri, Saeid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    von Rosen, Dietrich
    On the efficiency of bootstrap method into the analysis contingency table2011In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 104, no 2, p. 182-187Article in journal (Refereed)
    Abstract [en]

    The bootstrap method is a computer intensive statistical method that is widely used in performing nonparametric inference. Categorica ldata analysis,inparticular the analysis of contingency tables, is commonly used in applied field. This work considers nonparametric bootstrap tests for the analysis of contingency tables. There are only a few research papers which exploit this field. The p-values of tests in contingency tables are discrete and should be uniformly distributed under the null hypothesis. The results of this article show that corresponding bootstrap versions work better than the standard tests. Properties of the proposed tests are illustrated and discussed using Monte Carlo simulations. This article concludes with an analytical example that examines the performance of the proposed tests and the confidence interval of the association coefficient.

  • 20.
    Amiri, Saeid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    von Rosen, Dietrich
    SLU.
    Zwanzig, Silvelyn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    On the comparison of parametric and nonparametric bootstrap2008Report (Other academic)
  • 21. Amiri, Saeid
    et al.
    von Rosen, Dietrich
    Zwanzig, Silvelyn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    The SVM Approach for Box–Jenkins Models 2009In: REVSTAT-Statistical Journal, ISSN 1645-6726, Vol. 7, no 1, p. 23-36Article in journal (Refereed)
    Abstract [en]

    Support Vector Machine (SVM) is known in classification and regression modeling. It has been receiving attention in the application of nonlinear functions. The aim is to motivate the use of the SVM approach to analyze the time series models. This is an effort to assess the performance of SVM in comparison with ARMA model. The applicability of this approach for a unit root situation is also considered.

  • 22.
    Amiri, Saeid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Zwanzig, Silvelyn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    An Improvement of the Nonparametric Bootstrap Test for the Comparison of the Coefficient of Variations2010In: Communications in statistics. Simulation and computation, ISSN 0361-0918, E-ISSN 1532-4141, Vol. 39, no 9, p. 1726-1734Article in journal (Refereed)
    Abstract [en]

    In this article, we propose a new test for examining the equality of the coefficient of variation between two different populations. The proposed test is based on the nonparametric bootstrap method. It appears to yield several appreciable advantages over the current tests. The quick and easy implementation of the test can be considered as advantages of the proposed test. The test is examined by the Monte Carlo simulations, and also evaluated using various numerical studies.

  • 23.
    Amiri, Saeid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Zwanzig, Silvelyn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Assessing the coefficient of variations of chemical data using bootstrap method2011In: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 25, no 6, p. 295-300Article in journal (Refereed)
    Abstract [en]

    The coefficient of variation is frequently used in the comparison and precision of results with different scales. This work examines the comparison of the coefficient of variation without any assumptions about the underlying distribution. A family of tests based on the bootstrap method is proposed, and its properties are illustrated using Monte Carlo simulations. The proposed method is applied to chemical experiments with iid and non-iid observations.

  • 24. Anantharam, Venkat
    et al.
    Konstantopoulos, Takis
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Integral representation of skorokhod reflection2011In: Proceedings of the American Mathematical Society, ISSN 0002-9939, E-ISSN 1088-6826, Vol. 139, no 6, p. 2227-2237Article in journal (Refereed)
    Abstract [en]

    We show that a certain integral representation of the one-sided Skorokhod reflection of a continuous bounded variation function characterizes the reflection in that it possesses a unique maximal solution which solves the Skorokhod reflection problem.

  • 25.
    Backåker, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    The Google Markov Chain: convergence speed and eigenvalues2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 26.
    Baranzano, Rosa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Non-parametric kernel density estimation-based permutation test: Implementation and comparisons.2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 27. Barnsley, Michael
    et al.
    Hutchinson, John E.
    Stenflo, Örjan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    V-variable fractals: dimension results2012In: Forum mathematicum, ISSN 0933-7741, E-ISSN 1435-5337, Vol. 24, no 3, p. 445-470Article in journal (Refereed)
    Abstract [en]

    The families of V-variable fractals for V = 1, 2, ... , together with their natural probability distributions, interpolate between the corresponding families of random homogeneous fractals and of random recursive fractals. We investigate certain random V x V matrices associated with these fractals and use them to compute the almost sure Hausdorff dimension of V-variable fractals satisfying the uniform open set condition.

  • 28. Biermé, Hermine
    et al.
    Estrade, Anne
    Kaj, Ingemar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Self-similar random fields and rescaled random balls models2007Report (Other scientific)
    Abstract [en]

    We study generalized random fields which arise as rescaling limits of

    spatial configurations of uniformly scattered random balls as the mean

    radius of the balls tends to $0$ or infinity. Assuming that the radius

    distribution has a power law behavior, we prove that the centered and

    renormalized random balls field admits a limit with strong spatial

    dependence. In particular, our approach provides a unified framework

    to obtain all self-similar, translation and rotation

    invariant Gaussian fields.

    In addition to investigating stationarity and self-similarity

    properties, we give $L2$-representations of the asymptotic generalized

    random fields viewed as continuous random linear functionals.

  • 29. Biermé, Hermine
    et al.
    Estrade, Anne
    Kaj, Ingemar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Self-similar Random Fields and Rescaled Random Balls Models2010In: Journal of theoretical probability, ISSN 0894-9840, E-ISSN 1572-9230, Vol. 23, no 4, p. 1110-1141Article in journal (Refereed)
    Abstract [en]

    We study generalized random fields which arise as rescaling limits of spatial configurations of uniformly scattered random balls as the mean radius of the balls tends to 0 or infinity. Assuming that the radius distribution has a power-law behavior, we prove that the centered and renormalized random balls field admits a limit with self-similarity properties. Our main result states that all self-similar, translation-and rotation-invariant Gaussian fields can be obtained through a unified zooming procedure starting from a random balls model. This approach has to be understood as a microscopic description of macroscopic properties. Under specific assumptions, we also get a Poisson-type asymptotic field. In addition to investigating stationarity and self-similarity properties, we give L-2-representations of the asymptotic generalized random fields viewed as continuous random linear functionals.

  • 30. Britton, Tom
    et al.
    Lindholm, Mathias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Turova, Tatyana
    A dynamic network in a dynamic population: Asymptotic properties2011In: Journal of Applied Probability, ISSN 0021-9002, E-ISSN 1475-6072, Vol. 48, no 4, p. 1163-1178Article in journal (Refereed)
    Abstract [en]

    We derive asymptotic properties for a stochastic dynamic network model in a stochastic dynamic population. In the model, nodes give birth to new nodes until they die, each node being equipped with a social index given at birth. During the life of a node it creates edges to other nodes, nodes with high social index at higher rate, and edges disappear randomly in time. For this model, we derive a criterion for when a giant connected component exists after the process has evolved for a long period of time, assuming that the node population grows to infinity. We also obtain an explicit expression for the degree correlation rho (of neighbouring nodes) which shows that rho is always positive irrespective of parameter values in one of the two treated submodels, and may be either positive or negative in the other model, depending on the parameters.

  • 31.
    Cambronero, Christoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    The Brownian tree2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 32. de Vegt, Christian
    et al.
    Zwanzig, Silvelyn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Comparison of reference framelinking methods2001Report (Other scientific)
  • 33.
    Ding, Ding
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Modeling and simulation of highway traffic using a cellular automaton approach2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 34.
    Dombry, Clément
    et al.
    Poitiers University.
    Kaj, Ingemar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    The on-off network traffic model under intermediate scaling2011In: Queueing systems, ISSN 0257-0130, E-ISSN 1572-9443, Vol. 69, no 1, p. 29-44Article in journal (Refereed)
    Abstract [en]

    The result provided in this paper helps complete a unified picture of the scaling behavior in heavy-tailed stochastic models for transmission of packet traffic on high-speed communication links. Popular models include infinite source Poisson models, models based on aggregated renewal sequences, and models built from aggregated on---off sources. The versions of these models with finite variance transmission rate share the following pattern: if the sources connect at a fast rate over time the cumulative statistical fluctuations are fractional Brownian motion, if the connection rate is slow the traffic fluctuations are described by a stable Lévy motion, while the limiting fluctuations for the intermediate scaling regime are given by fractional Poisson motion. In this paper, we prove an invariance principle for the normalized cumulative workload of a network with m on---off sources and time rescaled by a factor a. When both the number of sources m and the time scale a tend to infinity with a relative growth given by the so-called 'intermediate connection rate' condition, the limit process is the fractional Poisson motion. The proof is based on a coupling between the on---off model and the renewal type model.

  • 35.
    Eklund, Martin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Zwanzig, Silvelyn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Ridge-SimSel: A generalization of the variable selection method SimSel to multicollinear data setsArticle in journal (Refereed)
  • 36.
    Eklund, Martin
    et al.
    Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioinformatics. Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Farmakologi.
    Zwanzig, Silvelyn
    Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioinformatics. Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. matematiska statistik.
    SimSel - a new simulation feature selection method I2007Report (Other scientific)
    Abstract [en]

    In pharmaceutical research there are datasets describing the interactions between proteins and molecules. The datasets include a huge number of independent variables (features) and the response variable is typically the binding strength. Thus, one of the most challenging problems is to find the features that have a real influence on the binding strength.

    Here we present a feature selection method. The principle of the algorithm is to disturb each single feature by adding pseudo errors and to study the influence on the quality of the model fit.

    The main idea is that the change of unimportant features has no effect on the binding strength.

  • 37.
    Eklund, Martin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Zwanzig, Silvelyn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    SimSel: a new simulation method for variable selection2012In: Journal of Statistical Computation and Simulation, ISSN 0094-9655, E-ISSN 1563-5163, Vol. 82, no 4, p. 515-527Article in journal (Refereed)
    Abstract [en]

    We propose a new simulation method, SimSel, for variable selection in linear and nonlinear modelling problems. SimSel works by disturbing the input data with pseudo-errors. We then study how this disturbance affects the quality of an approximative model fitted to the data. The main idea is that disturbing unimportant variables does not affect the quality of the model fit. The use of an approximative model has the advantage that the true underlying function does not need to be known and that the method becomes insensitive to model misspecifications. We demonstrate SimSel on simulated data from linear and nonlinear models and on two real data sets. The simulation studies suggest that SimSel works well in complicated situations, such as nonlinear errors-in-variable models.

  • 38.
    Eriksson, Måns
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Two simple tests for normality with high power2010Report (Other academic)
    Abstract [en]

    We derive explicit expressions for the correlation coefficients between the sample mean and the sample variance and between the sample mean and the third central sample moment in terms of sample moments. Using these we show that two tests for normality, proposed by Lin and Mudholkar (1980) and Mudholkar et al. (2002), can be simplified by using moment estimators; particularly the sample skewness and kurtosis; rather than the jackknife estimators previously used. In an extensive simulation power study the tests exhibit higher power than some common tests for normality against a wide range of distributions.

  • 39.
    Erixon, Per
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Systematic Botany.
    Svennblad, Bodil
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Britton, Tom
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Oxelman, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Systematic Botany.
    Reliability of Bayesian Posterior Probabilities and Bootstrap Frequencies in Phylogenetics2003In: Systematic Biology, ISSN 1063-5157, E-ISSN 1076-836X, Vol. 52, no 5, p. 665-673Article in journal (Refereed)
    Abstract [en]

    Many empirical studies have revealed considerable differences between nonparametric bootstrapping and Bayesian posterior probabilities in terms of the support values for branches, despite claimed predictions about their approximate equivalence. We investigated this problem by simulating data, which were then analyzed by maximum likelihood bootstrapping and Bayesian phylogenetic analysis using identical models and reoptimization of parameter values. We show that Bayesian posterior probabilities are significantly higher than corresponding nonparametric bootstrap frequencies for true clades, but also that erroneous conclusions will be made more often. These errors are strongly accentuated when the models used for analyses are underparameterized. When data are analyzed under the correct model, nonparametric bootstrapping is conservative. Bayesian posterior probabilities are also conservative in this respect, but less so.

  • 40. Fazekas, Istvan
    et al.
    Kukush, Alexander
    Zwanzig, Silvelyn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    On inconsistency of the least squares estimator in nonlinear functional relations1998Report (Other scientific)
  • 41. Fleischmann, K
    et al.
    Gartner, J
    Kaj, I
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    A Schilder type theorem for super-Brownian motion1996In: CANADIAN JOURNAL OF MATHEMATICS-JOURNAL CANADIEN DE MATHEMATIQUES, Vol. 48, no 3, p. 542-568Article in journal (Refereed)
    Abstract [en]

    Let X be a d-dimensional continuous super-Brownian motion with branching rate epsilon, which might be described symbolically by the ''stochastic equation'' dX(t) = Delta*X(t)dt + root 2 epsilon X(t)dW(t) with dW(t)/dt a space-time white noise. A Schilder

  • 42.
    Folkvaljon, Yasin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Predicting Gleason score upgrading and downgrading between biopsy Gleason score and prostatectomy Gleason score – A population-based cohort study2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 43.
    Gaigalas, Raimundas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    A Poisson bridge between fractional Brownian motion and stable Levy motion2006In: Stochastic Processes and their Applications, Vol. 116, no 3, p. 447-462Article in journal (Refereed)
  • 44.
    Gong, Sheng
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Estimation of hot and cold spells with extreme value theory2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 45. Grimmet, Geoffrey
    et al.
    Janson, Svante
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Scudo, Petra F.
    Weak limits for quantum random walks2003Report (Other scientific)
  • 46.
    Gräns, Gustaf
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Visualisering av marknadsstatistik2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this master thesis was to explore and develop prototypes for visualization of trade statistics in a market surveilance application. In such an anapplication a large amount of information is processed. This information is then summarized and presented to the market surveillance staff. The practical part of this thesis was done at Scila AB in Stockholm. Three prototypes were developed based on modern visualization methods. Another graph that already existed in the application was improved. The graphs were then evaluated with the help of simulated market data. Two of the graphs were also evaluated using real market data. Finally the graphs were demonstrated to market surveillance staff from an exchange in Stockholm. The conclusion was that two of the graphs have potential to be useful while the same can't be said for the other two.

  • 47.
    Gunnarsson, Niklas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Modeling sensor networks with mobile nodes2006Licentiate thesis, monograph (Other scientific)
  • 48.
    Gunnarsson, Niklas
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Kaj, Ingemar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Mannersalo, Petteri
    A growth model for Brownian sensors2006Report (Other scientific)
  • 49.
    Gunnarsson, Niklas
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Kaj, Ingemar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics. Matematisk statistik.
    Mannersalo, Petteri
    Propagation properties for a message in a Brownian sensor network2006Report (Other scientific)
  • 50.
    Gustafsson, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics, Mathematical Statistics.
    Statistisk analys av symptomfrihet efter elektrokonvulsiv behandling2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
12345 1 - 50 of 224
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