The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
R. Manoharan - One of the best experts on this subject based on the ideXlab platform.
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Exponential Reliability Coefficient based Reputation Mechanism for isolating selfish nodes in MANETs
Egyptian Informatics Journal, 2015Co-Authors: J. Sengathir, R. ManoharanAbstract:Abstract In mobile ad hoc networks, cooperation among active mobile nodes is considered to play a vital role in reliable transmission of data. But, the selfish mobile nodes present in an ad hoc environment refuse to forward neighbouring nodes’ packet for conserving its own energy. This intentional selfish behaviour drastically reduces the degree of cooperation maintained between the mobile nodes. Hence, a need arises for devising an effective mechanism which incorporates both energy efficiency and reputation into account for mitigating selfish behaviour in MANETs. In this paper, we propose an Exponential Reliability Coefficient based reputation Mechanism (ERCRM) which isolates the selfish nodes from the routing path based on Exponential Reliability Coefficient (ExRC). This Reliability Coefficient manipulated through exponential failure rate based on moving average method highlights the most recent past behaviour of the mobile nodes for quantifying its genuineness. From the simulation results, it is evident that, the proposed ERCRM approach outperforms the existing Packet Conservation Monitoring Algorithm (PCMA) and Spilt Half Reliability Coefficient based Mathematical Model (SHRCM) in terms of performance evaluation metrics such as packet delivery ratio, throughput, total overhead and control overhead. Further, this ERCRM mechanism has a successful rate of 28% in isolating the selfish nodes from the routing path. Furthermore, it also aids in framing the exponential threshold point of detection as 0.4, where a maximum number of selfish nodes are identified when compared to the existing models available in the literature.
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a split half Reliability Coefficient based mathematical model for mitigating selfish nodes in manets
IEEE International Advance Computing Conference, 2013Co-Authors: J. Sengathir, R. ManoharanAbstract:The data dissemination among the wireless nodes in an ad hoc environment mainly depends on the cooperation maintained between them. This co-operation is essential for establishing both forward and reverse route as well as relaying the packets. Due to the limited availability of resources in an ad hoc scenario, some of the nodes may tend to drop the packets coming from their neighbor nodes while forwarding their own packets. This type of node's behavior is known as “selfish behavior”. In this paper, we devise and propose a mathematical model that could detect the selfish nodes based on the split half Reliability co-efficient. This split half Reliability is a two level consistency check mechanism, which is based on the aggregate number of packets entering and leaving a node at a time instant. The effective performance of the devised mathematical model is studied through ns-2 simulation with the help of parameters namely packet delivery ratio, control overhead, total overhead and throughput by varying the number of selfish nodes. The results of the experimental study depicts that this proposed model could detect the selfish nodes rapidly when compared to any other existing models available in the literature.
Yao Shuqiao - One of the best experts on this subject based on the ideXlab platform.
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Reliability and validity of adaptive skill rating scale for children
Chinese journal of clinical psychology, 2003Co-Authors: Yao ShuqiaoAbstract:Objective:To investigate the Reliability and validity of the Adaptive Skill Rating Scale for Children(ASRSC).Methods:The internal consistency Reliability,test-retest Reliability and inter-rater Reliability were examined.A factor analysis procedure was used to explore the factor structure of ASRSC.The criterion-related validity was evaluated through correlating ASRSC with C-WISC and Child Adaptive Behavior Scale(CABS).Results:(1)Cronbach's α coefficents of the four domains of ASRSC ranged from 0.32 to 0.99;The split-half reliablity Coefficients for four domains were 0.92～0.99;The test-retest Reliability Coefficient of the total score was 0.98;The interrater-Reliability Coefficient of the total score was 0.98;(2)One factor emerged following varimax rotation;The correlation between the total scores of ASRSC and C-WISC and CABS were 0.36,0.67 respectively.Conclusion:The Reliability and validity of ASRSC were psychometrically acceptable.
Audrey L. Qualls - One of the best experts on this subject based on the ideXlab platform.
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Variability in Reliability Coefficients and the Standard Error of Measurement From School District to District
Applied Measurement in Education, 1999Co-Authors: Leonard S. Feldt, Audrey L. QuallsAbstract:Measurement textbooks frequently suggest that Reliability Coefficients will be lower in more homogeneous groups. This expected relation rests on the assumption of constancy in the standard error of measurement (SEM) and that the lower observed-score variance is the result of lower true-score variance. However, the assumption of constancy in the SEM can be challenged on both theoretical and empirical grounds. It is possible that a more heterogeneous group might have a relatively large error score variance and hence, a lower Reliability Coefficient. In this study, the stability of the SEM and the relation between the Reliability Coefficient and the variance of both true scores and error scores were empirically examined for 170 school districts within a state. As expected, rXX´ was found to vary as a function of group variability. However, the Coefficient was not found to be solely a function of the magnitude of true-score variance. Rather, it depended on error variance as well, and particularly on the ratio...
Leonard S. Feldt - One of the best experts on this subject based on the ideXlab platform.
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Estimating the Effect of Changes in Criterion Score Reliability on the Power of the F Test of Equality of Means
Educational and Psychological Measurement, 2011Co-Authors: Leonard S. FeldtAbstract:This article presents a simple, computer-assisted method of determining the extent to which increases in Reliability increase the power of the F test of equality of means. The method uses a derived formula that relates the changes in the Reliability Coefficient to changes in the noncentrality of the relevant F distribution. A readily available computer applet translates the noncentrality parameter into the power value of the F test.
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The estimation of the IRT Reliability Coefficient and its lower and upper bounds, with comparisons to CTT Reliability statistics
Asia Pacific Education Review, 2010Co-Authors: Seonghoon Kim, Leonard S. FeldtAbstract:The primary purpose of this study is to investigate the mathematical characteristics of the test Reliability Coefficient ρXX′ as a function of item response theory (IRT) parameters and present the lower and upper bounds of the Coefficient. Another purpose is to examine relative performances of the IRT Reliability statistics and two classical test theory (CTT) Reliability statistics (Cronbach’s alpha and Feldt–Gilmer congeneric Coefficients) under various testing conditions that result from manipulating large-scale real data. For the first purpose, two alternative ways of exactly quantifying ρXX′ are compared in terms of computational efficiency and statistical usefulness. In addition, the lower and upper bounds for ρXX′ are presented in line with the assumptions of essential tau-equivalence and congeneric similarity, respectively. Empirical studies conducted for the second purpose showed across all testing conditions that (1) the IRT Reliability Coefficient was higher than the CTT Reliability statistics; (2) the IRT Reliability Coefficient was closer to the Feldt–Gilmer Coefficient than to the Cronbach’s alpha Coefficient; and (3) the alpha Coefficient was close to the lower bound of IRT Reliability. Some advantages of the IRT approach to estimating test-score Reliability over the CTT approaches are discussed in the end.
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Variability in Reliability Coefficients and the Standard Error of Measurement From School District to District
Applied Measurement in Education, 1999Co-Authors: Leonard S. Feldt, Audrey L. QuallsAbstract:Measurement textbooks frequently suggest that Reliability Coefficients will be lower in more homogeneous groups. This expected relation rests on the assumption of constancy in the standard error of measurement (SEM) and that the lower observed-score variance is the result of lower true-score variance. However, the assumption of constancy in the SEM can be challenged on both theoretical and empirical grounds. It is possible that a more heterogeneous group might have a relatively large error score variance and hence, a lower Reliability Coefficient. In this study, the stability of the SEM and the relation between the Reliability Coefficient and the variance of both true scores and error scores were empirically examined for 170 school districts within a state. As expected, rXX´ was found to vary as a function of group variability. However, the Coefficient was not found to be solely a function of the magnitude of true-score variance. Rather, it depended on error variance as well, and particularly on the ratio...
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Test of the Hypothesis that the Intraclass Reliability Coefficient Is the Same for Two Measurement Procedures.
Applied Psychological Measurement, 1992Co-Authors: Yousef M. Alsawalmeh, Leonard S. FeldtAbstract:An approximate statistical test is derived for the hypothesis that the intraclass Reliability Coefficients associated with two measurement procedures are equal. Control of Type 1 error is investigated by comparing empirical sampling distributions of the test statistic with its derived theoretical distribu tion. A numerical illustration of the procedure is also presented.
J. Sengathir - One of the best experts on this subject based on the ideXlab platform.
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Exponential Reliability Coefficient based Reputation Mechanism for isolating selfish nodes in MANETs
Egyptian Informatics Journal, 2015Co-Authors: J. Sengathir, R. ManoharanAbstract:Abstract In mobile ad hoc networks, cooperation among active mobile nodes is considered to play a vital role in reliable transmission of data. But, the selfish mobile nodes present in an ad hoc environment refuse to forward neighbouring nodes’ packet for conserving its own energy. This intentional selfish behaviour drastically reduces the degree of cooperation maintained between the mobile nodes. Hence, a need arises for devising an effective mechanism which incorporates both energy efficiency and reputation into account for mitigating selfish behaviour in MANETs. In this paper, we propose an Exponential Reliability Coefficient based reputation Mechanism (ERCRM) which isolates the selfish nodes from the routing path based on Exponential Reliability Coefficient (ExRC). This Reliability Coefficient manipulated through exponential failure rate based on moving average method highlights the most recent past behaviour of the mobile nodes for quantifying its genuineness. From the simulation results, it is evident that, the proposed ERCRM approach outperforms the existing Packet Conservation Monitoring Algorithm (PCMA) and Spilt Half Reliability Coefficient based Mathematical Model (SHRCM) in terms of performance evaluation metrics such as packet delivery ratio, throughput, total overhead and control overhead. Further, this ERCRM mechanism has a successful rate of 28% in isolating the selfish nodes from the routing path. Furthermore, it also aids in framing the exponential threshold point of detection as 0.4, where a maximum number of selfish nodes are identified when compared to the existing models available in the literature.
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a split half Reliability Coefficient based mathematical model for mitigating selfish nodes in manets
IEEE International Advance Computing Conference, 2013Co-Authors: J. Sengathir, R. ManoharanAbstract:The data dissemination among the wireless nodes in an ad hoc environment mainly depends on the cooperation maintained between them. This co-operation is essential for establishing both forward and reverse route as well as relaying the packets. Due to the limited availability of resources in an ad hoc scenario, some of the nodes may tend to drop the packets coming from their neighbor nodes while forwarding their own packets. This type of node's behavior is known as “selfish behavior”. In this paper, we devise and propose a mathematical model that could detect the selfish nodes based on the split half Reliability co-efficient. This split half Reliability is a two level consistency check mechanism, which is based on the aggregate number of packets entering and leaving a node at a time instant. The effective performance of the devised mathematical model is studied through ns-2 simulation with the help of parameters namely packet delivery ratio, control overhead, total overhead and throughput by varying the number of selfish nodes. The results of the experimental study depicts that this proposed model could detect the selfish nodes rapidly when compared to any other existing models available in the literature.
