926 resultados para Item sets


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In a series of three experiments, participants made inferences about which one of a pair of two objects scored higher on a criterion. The first experiment was designed to contrast the prediction of Probabilistic Mental Model theory (Gigerenzer, Hoffrage, & Kleinbölting, 1991) concerning sampling procedure with the hard-easy effect. The experiment failed to support the theory's prediction that a particular pair of randomly sampled item sets would differ in percentage correct; but the observation that German participants performed practically as well on comparisons between U.S. cities (many of which they did not even recognize) than on comparisons between German cities (about which they knew much more) ultimately led to the formulation of the recognition heuristic. Experiment 2 was a second, this time successful, attempt to unconfound item difficulty and sampling procedure. In Experiment 3, participants' knowledge and recognition of each city was elicited, and how often this could be used to make an inference was manipulated. Choices were consistent with the recognition heuristic in about 80% of the cases when it discriminated and people had no additional knowledge about the recognized city (and in about 90% when they had such knowledge). The frequency with which the heuristic could be used affected the percentage correct, mean confidence, and overconfidence as predicted. The size of the reference class, which was also manipulated, modified these effects in meaningful and theoretically important ways.

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Multi-relational data mining enables pattern mining from multiple tables. The existing multi-relational mining association rules algorithms are not able to process large volumes of data, because the amount of memory required exceeds the amount available. The proposed algorithm MRRadix presents a framework that promotes the optimization of memory usage. It also uses the concept of partitioning to handle large volumes of data. The original contribution of this proposal is enable a superior performance when compared to other related algorithms and moreover successfully concludes the task of mining association rules in large databases, bypass the problem of available memory. One of the tests showed that the MR-Radix presents fourteen times less memory usage than the GFP-growth. © 2011 IEEE.

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It is important to check the fundamental assumption of most popular Item Response Theory models, unidimensionality. However, it is hard for educational and psychological tests to be strictly unidimensional. The tests studied in this paper are from a standardized high-stake testing program. They feature potential multidimensionality by presenting various item types and item sets. Confirmatory factor analyses with one-factor and bifactor models, and based on both linear structural equation modeling approach and nonlinear IRT approach were conducted. The competing models were compared and the implications of the bifactor model for checking essential unidimensionality were discussed.

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Background: Despite initial concerns about the sensitivity of the proposed diagnostic criteria for DSM-5 Autism Spectrum Disorder (ASD; e.g. Gibbs et al., 2012; McPartland et al., 2012), evidence is growing that the DSM-5 criteria provides an inclusive description with both good sensitivity and specificity (e.g. Frazier et al., 2012; Kent, Carrington et al., 2013). The capacity of the criteria to provide high levels of sensitivity and specificity comparable with DSM-IV-TR however relies on careful measurement to ensure that appropriate items from diagnostic instruments map onto the new DSM-5 descriptions.Objectives: To use an existing DSM-5 diagnostic algorithm (Kent, Carrington et .al., 2013) to identify a set of ‘essential’ behaviors sufficient to make a reliable and accurate diagnosis of DSM-5 Autism Spectrum Disorder (ASD) across age and ability level. Methods: Specific behaviors were identified and tested from the recently published DSM-5 algorithm for the Diagnostic Interview for Social and Communication Disorders (DISCO). Analyses were run on existing DISCO datasets, with a total participant sample size of 335. Three studies provided step-by-step development towards identification of a minimum set of items. Study 1 identified the most highly discriminating items (p<.0001). Study 2 used a lower selection threshold than in Study 1 (p<.05) to facilitate better representation of the full DSM-5 ASD profile. Study 3 included additional items previously reported as significantly more frequent in individuals with higher ability. The discriminant validity of all three item sets was tested using Receiver Operating Characteristic curves. Finally, sensitivity across age and ability was investigated in a subset of individuals with ASD (n=190).Results: Study 1 identified an item set (14 items) with good discriminant validity, but which predominantly measured social-communication behaviors (11/14). The Study 2 item set (48 items) better represented the DSM-5 ASD and had good discriminant validity, but the item set lacked sensitivity for individuals with higher ability. The final Study 3 adjusted item set (54 items) improved sensitivity for individuals with higher ability and performance and was comparable to the published DISCO DSM-5 algorithm.Conclusions: This work represents a first attempt to derive a reduced set of behaviors for DSM-5 directly from an existing standardized ASD developmental history interview. Further work involving existing ASD diagnostic tools with community-based and well characterized research samples will be required to replicate these findings and exploit their potential to contribute to a more efficient and focused ASD diagnostic process.

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A Gross Motor Function Measure (GMFM) é a medida de ouro para avaliar alterações na função motora ao longo do tempo ou em resposta a uma intervenção em crianças com Paralisia Cerebral (PC) (Russell D. , Rosenbaum, Avery, & Lane, 2002). Uma das barreiras à utilização mais frequente da GMFM é o seu tempo de administração, que dura entre 40 a 60 minutos. Para responder à necessidade de versões mais reduzidas da GMFM mas sem perder o seu carácter discriminativo e altamente sensível à mudança, foram publicadas as versões Gross Motor Function Measure- Item Sets (GMFM-66 IS) e a Gross Motor Function Measure Basal and Ceiling (GMFM-66-B&C), tornando a avaliação da função motora menos morosa, e assim melhorando a sua aplicabilidade. A GMFM-66 IS baseia-se num algoritmo para determinar quais os itens a serem avaliados e a GMFM-66 B&C tem como abordagem os efeitos de chão e teto de acordo com as idades e níveis do Sistema de Classificação da Função Motora Grosseira (SCFMG) (Brutton & Bartlett, 2011). O objetivo deste estudo foi criar as versões portuguesas da GMFM-IS e GMFM-B&C. Tratou-se de um estudo de natureza metodológica, descritivo, longitudinal em crianças com PC, dividido em duas fases: 1. Tradução e adaptação cultural e linguística da GMFM-66 IS e da GMFM-66 B&C; 2. Estudo de validação com análise da fiabilidade (coerência interna, reprodutibilidade e fiabilidade inter-observador), validade e poder de resposta. A amostra em estudo foi constituída por 100 crianças com PC com idades compreendidas entre os 2 e os 12 anos, representativa de todos os 5 níveis do Sistema de Classificação da Função Motora Global. As versões portuguesas da GMFM-66-IS e da GMFM-66-B&C apresentam equivalência conceptual e semântica com as versões originais revelando fácil aplicabilidade. Demonstrou-se que as versões reduzidas portuguesas da GMFM apresentam muito boa consistência interna, com valores globais do Alfa de Cronbach de 0,998, muito boa concordância entre os avaliadores (ICC de 0,998 para a GMFM-66-B&C e de 0,999 para a GMFM-66-IS), e com valores de fiabilidade intra-observador excelentes (ICC de 0,999 para a GMFM-66-B&C e de 1,000 para a GMFM-66-IS). Quanto ao poder de resposta os resultados não foram tão expressivos, provavelmente comprometidos por uma amostra demasiado pequena. As versões portuguesas da GMFM-66-IS e da GMFM-66-B&C revelaram ter características psicométricas adequadas à sua aplicação em PC, necessitando, no entanto, de mais investigação relativamente à sua capacidade de detetar mudança como resultado de intervenções.

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We are looking into variants of a domination set problem in social networks. While randomised algorithms for solving the minimum weighted domination set problem and the minimum alpha and alpha-rate domination problem on simple graphs are already present in the literature, we propose here a randomised algorithm for the minimum weighted alpha-rate domination set problem which is, to the best of our knowledge, the first such algorithm. A theoretical approximation bound based on a simple randomised rounding technique is given. The algorithm is implemented in Python and applied to a UK Twitter mentions networks using a measure of individuals’ influence (klout) as weights. We argue that the weights of vertices could be interpreted as the costs of getting those individuals on board for a campaign or a behaviour change intervention. The minimum weighted alpha-rate dominating set problem can therefore be seen as finding a set that minimises the total cost and each individual in a network has at least alpha percentage of its neighbours in the chosen set. We also test our algorithm on generated graphs with several thousand vertices and edges. Our results on this real-life Twitter networks and generated graphs show that the implementation is reasonably efficient and thus can be used for real-life applications when creating social network based interventions, designing social media campaigns and potentially improving users’ social media experience.