Global ETD Search

21	排列檢定法應用於空間資料之比較 / Permutation test on spatial comparison 王信忠, Wang, Hsin-Chung Unknown Date (has links) 本論文主要是探討在二維度空間上二母體分佈是否一致。我們利用排列 (permutation)檢定方法來做比較, 並藉由費雪(Fisher)正確檢定方法的想法而提出重標記 (relabel)排列檢定方法或稱為費雪排列檢定法。我們透過可交換性的特質證明它是正確 (exact) 的並且比 Syrjala (1996)所建議的排列檢定方法有更高的檢定力 (power)。本論文另提出二個空間模型: spatial multinomial-relative-log-normal 模型與 spatial Poisson-relative-log-normal 模型來配適一般在漁業中常有的右斜長尾次數分佈並包含很多0 的空間資料。另外一般物種可能因天性或自然環境因素像食物、溫度等影響而有群聚行為發生, 這二個模型亦可描述出空間資料的群聚現象以做適當的推論。 / This thesis proposes the relabel (Fisher's) permutation test inspired by Fisher's exact test to compare between distributions of two (fishery) data sets locating on a two-dimensional lattice. We show that the permutation test given by Syrjala (1996} is not exact, but our relabel permutation test is exact and, additionally, more powerful. This thesis also studies two spatial models: the spatial multinomial-relative-log-normal model and the spatial Poisson-relative-log-normal model. Both models not only exhibit characteristics of skewness with a long right-hand tail and of high proportion of zero catches which usually appear in fishery data, but also have the ability to describe various types of aggregative behaviors. 費雪(Fisher)正確檢定 Cramer-von Mises 統計量排列檢定可交換性空間分佈貝氏(Bayesian)方法檢定力比較空間自我迴歸(CAR)模型 auto-Poisson模型 auto-Gaussian模型群聚 Fisher's exact test Cramer-von Mises statistic permutation test exchangeable spatial distributions Bayesian approach power comparison auto-Poisson model auto-Gaussian model cluster
22	Methods for face detection and adaptive face recognition Pavani, Sri-Kaushik 21 July 2010 (has links) The focus of this thesis is on facial biometrics; specifically in the problems of face detection and face recognition. Despite intensive research over the last 20 years, the technology is not foolproof, which is why we do not see use of face recognition systems in critical sectors such as banking. In this thesis, we focus on three sub-problems in these two areas of research. Firstly, we propose methods to improve the speed-accuracy trade-off of the state-of-the-art face detector. Secondly, we consider a problem that is often ignored in the literature: to decrease the training time of the detectors. We propose two techniques to this end. Thirdly, we present a detailed large-scale study on self-updating face recognition systems in an attempt to answer if continuously changing facial appearance can be learnt automatically. / L'objectiu d'aquesta tesi és sobre biometria facial, específicament en els problemes de detecció de rostres i reconeixement facial. Malgrat la intensa recerca durant els últims 20 anys, la tecnologia no és infalible, de manera que no veiem l'ús dels sistemes de reconeixement de rostres en sectors crítics com la banca. En aquesta tesi, ens centrem en tres sub-problemes en aquestes dues àrees de recerca. En primer lloc, es proposa mètodes per millorar l'equilibri entre la precisió i la velocitat del detector de cares d'última generació. En segon lloc, considerem un problema que sovint s'ignora en la literatura: disminuir el temps de formació dels detectors. Es proposen dues tècniques per a aquest fi. En tercer lloc, es presenta un estudi detallat a gran escala sobre l'auto-actualització dels sistemes de reconeixement facial en un intent de respondre si el canvi constant de l'aparença facial es pot aprendre de forma automàtica. Fisher's LDA Gaussian weak classifiers Weak classifier Variance normalization Transductive reasoning training complexity rejection cascade fusion of p-values OSTCM-kNN classifier integrated Performance Primitives impostor detection haar-like features fusion of shape and texture face recognition system delaunay triangulation MIT+CMU face database YT database GEFA database temporal confidence segmentation confidence face detector confidence classification confidence laplacian clutter model clutter models changes in facial appearance face segmentation face normalization face detection automatic face recognition system 62
23	IT’S IN THE DATA 2 : A study on how effective design of a digital product’s user onboarding experience can increase user retention Fridell, Gustav January 2021 (has links) User retention is a key factor for Software as a Service (SaaS) companies to ensure long-term growth and profitability. One area which can have a lasting impact on a digital product’s user retention is its user onboarding experience, that is, the methods and elements that guide new users to become familiar with the product and activate them to become fully registered users. Within the area of user onboarding, multiple authors discuss “best practice” design patterns which are stated to positively influence the user retention of new users. However, none of the sources reviewed showcase any statistically significant proof of this claim. Thus, the objective of this study was to: Design and implement a set of commonly applied design patterns within a digital product’s user onboarding experience and evaluate their effects on user retention Through A/B testing on the SaaS product GetAccept, the following two design patterns were evaluated: Reduce friction – reducing the number of barriers and steps for a new user when first using a digital product; and Monitor progress – monitoring and clearly showcasing the progress of a new user’s journey when first using a digital product. The retention metric used to evaluate the two design patterns was first week user retention, defined as the share of customers who after signing up, sign in again at least once within one week. This was tested by randomly assigning new users into different groups: groups that did receive changes related to the design patterns, and one group did not receive any changes. By then comparing the first week user retention data between the groups using Fisher’s exact test, the conclusion could be drawn that with statistical significance, both of the evaluated design patterns positively influenced user retention for GetAccept. Furthermore, due to the generalizable nature of GetAccept’s product and the aspects evaluated, this conclusion should also be applicable to other companies and digital products with similar characteristics, and the method used to evaluate the impact of implementing the design patterns should be applicable for evaluating other design patterns and/or changes in digital products. However, as the method used for data collection in the study could not ensure full validity of it, the study could and should be repeated with the same design patterns on another digital product and set of users in order to strengthen the reliability of the conclusions drawn. saas software as a service software-as-a-service data-driven data driven analytics A/B testing A/B-testing AB testing AB-testing bucket testing split-run testing web web development application design design pattern programming software Fisher's exact test Fisher exact test growth onboarding onboarding experience retention user retention churn digital product digital statistics user onboarding customer profitability Computer and Information Sciences Data- och informationsvetenskap Probability Theory and Statistics Sannolikhetsteori och statistik Human Computer Interaction Software Engineering Programvaruteknik Business Administration Företagsekonomi

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