Model evaluation

Xem 1-20 trên 641 kết quả Model evaluation
  • Given a collection of records (training set ) Each record contains a set of attributes, one of the attributes is the class. Find a model for class attribute as a function of the values of other attributes. Goal: previously unseen records should be assigned a class as accurately as possible. A test set is used to determine the accuracy of the model. Usually, the given data set is divided into training and test sets, with training set used to build the model and test set used to validate it.

    ppt101p trinh02 18-01-2013 45 8   Download

  • All questions are implicitly associated with an expected answer type. Unlike previous approaches that require a predefined set of question types, we present a method for dynamically constructing a probability-based answer type model for each different question. Our model evaluates the appropriateness of a potential answer by the probability that it fits into the question contexts. Evaluation is performed against manual and semiautomatic methods using a fixed set of answer labels.

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  • Since the seminal study of Leland, Taqqu, Willinger, and Wilson [41], which set the groundwork for considering self-similarity an important notion in the understanding of network traffic including the modeling and analysis of network performance, an explosion of work has ensued investigating the multifaceted nature of this phenomenon.

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  • 2. The computational inter-relationships between data types are complex: eg rainfall/soil type/location/species. A Generic model can evaluate a variety of separate investment projects for a variety of users.

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  • Having a vision, a mission, and a passion are invariably seen as conditions for success. The 1995 U.S. Department of Health and Human Services (DHHS) concept of a Metropolitan Medical Response System (MMRS) demonstrated that the leaders of DHHS had a vision for an effective response to a mass-casualty terrorism incident with a weapon of mass destruction. The mission was to expand the experimental model of the Metropolitan Medical Strike Team (MMST) established in Washington, D.C., and neighboring counties into a national program.

    pdf331p hyperion75 22-01-2013 22 4   Download

  • This paper proposes a novel method for learning probability models of subcategorization preference of verbs. We consider the issues of case dependencies and noun class generalization in a uniform way by employing the maximum entropy modeling method. We also propose a new model selection algorithm which starts from the most general model and gradually examines more specific models.

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  • Tham khảo sách 'modelling simulation and optimization', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

    pdf330p kimngan_1 05-11-2012 29 3   Download

  • We consider the problem of correcting errors made by English as a Second Language (ESL) writers and address two issues that are essential to making progress in ESL error correction - algorithm selection and model adaptation to the first language of the ESL learner. A variety of learning algorithms have been applied to correct ESL mistakes, but often comparisons were made between incomparable data sets. We conduct an extensive, fair comparison of four popular learning methods for the task, reversing conclusions from earlier evaluations. ...

    pdf10p hongdo_1 12-04-2013 23 3   Download

  • We present a novel model to represent and assess the discourse coherence of text. Our model assumes that coherent text implicitly favors certain types of discourse relation transitions. We implement this model and apply it towards the text ordering ranking task, which aims to discern an original text from a permuted ordering of its sentences.

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  • Active Learning (AL) is typically initialized with a small seed of examples selected randomly. However, when the distribution of classes in the data is skewed, some classes may be missed, resulting in a slow learning progress. Our contribution is twofold: (1) we show that an unsupervised language modeling based technique is effective in selecting rare class examples, and (2) we use this technique for seeding AL and demonstrate that it leads to a higher learning rate. The evaluation is conducted in the context of word sense disambiguation. ...

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  • We investigate the empirical behavior of ngram discounts within and across domains. When a language model is trained and evaluated on two corpora from exactly the same domain, discounts are roughly constant, matching the assumptions of modified Kneser-Ney LMs. However, when training and test corpora diverge, the empirical discount grows essentially as a linear function of the n-gram count. We adapt a Kneser-Ney language model to incorporate such growing discounts, resulting in perplexity improvements over modified Kneser-Ney and Jelinek-Mercer baselines. ...

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  • We present a global joint model for lemmatization and part-of-speech prediction. Using only morphological lexicons and unlabeled data, we learn a partiallysupervised part-of-speech tagger and a lemmatizer which are combined using features on a dynamically linked dependency structure of words. We evaluate our model on English, Bulgarian, Czech, and Slovene, and demonstrate substantial improvements over both a direct transduction approach to lemmatization and a pipelined approach, which predicts part-of-speech tags before lemmatization. ...

    pdf9p hongphan_1 14-04-2013 19 3   Download

  • This paper reports the development of loglinear models for the disambiguation in wide-coverage HPSG parsing. The estimation of log-linear models requires high computational cost, especially with widecoverage grammars. Using techniques to reduce the estimation cost, we trained the models using 20 sections of Penn Treebank. A series of experiments empirically evaluated the estimation techniques, and also examined the performance of the disambiguation models on the parsing of real-world sentences. ...

    pdf8p bunbo_1 17-04-2013 17 3   Download

  • We present an empirical study of the applicability of Probabilistic Lexicalized Tree Insertion Grammars (PLTIG), a lexicalized counterpart to Probabilistic Context-Free Grammars (PCFG), to problems in stochastic naturallanguage processing. Comparing the performance of PLTIGs with non-hierarchical N-gram models and PCFGs, we show that PLTIG combines the best aspects of both, with language modeling capability comparable to N-grams, and improved parsing performance over its nonlexicalized counterpart. Furthermore, training of PLTIGs displays faster convergence than PCFGs. ...

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  • Tham khảo sách 'an educator s guide to evaluating the use of technology in schools', kỹ thuật - công nghệ, kĩ thuật viễn thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

    pdf119p nt18101 29-04-2013 14 3   Download

  • For a natural language access to database system to be practical it must achieve a good match between the capabilities of the user and the requirements of the task. The user brings his own natural language and his own style of interaction to the system. The task brings the questions that must be answered and the database domaln+s semantics. All natural language access systems achieve some degree of success. But to make progress as a field, we need to be able to evaluate the degree of this success. For too long, the best we have menaged has been to...

    pdf2p bungio_1 03-05-2013 17 3   Download

  • Automated essay scoring is now an established capability used from elementary school through graduate school for purposes of instruction and assessment. Newer applications provide automated diagnostic feedback about student writing. Feedback includes errors in grammar, usage, and mechanics, comments about writing style, and evaluation of discourse structure. This paper reports on a system that evaluates a characteristic of lower quality essay writing style: repetitious word use.

    pdf8p bunthai_1 06-05-2013 27 3   Download

  • In this paper a novel solution to automatic and unsupervised word sense induction (WSI) is introduced. It represents an instantiation of the ‘one sense per collocation’ observation (Gale et al., 1992). Like most existing approaches it utilizes clustering of word co-occurrences. This approach differs from other approaches to WSI in that it enhances the effect of the one sense per collocation observation by using triplets of words instead of pairs. The combination with a two-step clustering process using sentence co-occurrences as features allows for accurate results.

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  • A major focus of current work in distributional models of semantics is to construct phrase representations compositionally from word representations. However, the syntactic contexts which are modelled are usually severely limited, a fact which is reflected in the lexical-level WSD-like evaluation methods used.

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  • In this work I address the challenge of augmenting n-gram language models according to prior linguistic intuitions. I argue that the family of hierarchical Pitman-Yor language models is an attractive vehicle through which to address the problem, and demonstrate the approach by proposing a model for German compounds. In an empirical evaluation, the model outperforms the Kneser-Ney model in terms of perplexity, and achieves preliminary improvements in English-German translation.

    pdf10p bunthai_1 06-05-2013 28 3   Download


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