Showing papers on "Proxy (statistics) published in 2006"
TL;DR: Performance measurements of the experimental file system demonstrate the usefulness of proxy re-encryption as a method of adding access control to a secure file system and present new re-Encryption schemes that realize a stronger notion of security.
Abstract: In 1998, Blaze, Bleumer, and Strauss (BBS) proposed an application called atomic proxy re-encryption, in which a semitrusted proxy converts a ciphertext for Alice into a ciphertext for Bob without seeing the underlying plaintext. We predict that fast and secure re-encryption will become increasingly popular as a method for managing encrypted file systems. Although efficiently computable, the wide-spread adoption of BBS re-encryption has been hindered by considerable security risks. Following recent work of Dodis and Ivan, we present new re-encryption schemes that realize a stronger notion of security and demonstrate the usefulness of proxy re-encryption as a method of adding access control to a secure file system. Performance measurements of our experimental file system demonstrate that proxy re-encryption can work effectively in practice.
1,598 citations
TL;DR: This article found that the relationship between current and lifetime earnings departs substantially from the textbook errors-in-variables model in ways that vary systematically over the life cycle, which can enable more appropriate analysis of, and correction for, errors in variance bias in any research that uses current earnings to proxy for lifetime earnings.
Abstract: Researchers in a variety of important economic literatures have assumed that current income variables as proxies for lifetime income variables follow the textbook errors-in-variables model. In our analysis of Social Security records containing nearly career-long earnings histories for the Health and Retirement Study sample, we find that the relationship between current and lifetime earnings departs substantially from the textbook model in ways that vary systematically over the life cycle. Our results can enable more appropriate analysis of, and correction for, errors-in-variables bias in any research that uses current earnings to proxy for lifetime earnings. (JEL D31, D91)
552 citations
TL;DR: In this paper, the authors consider four econometric approaches to the problem that involve the use of multiple proxies for college quality: factor analysis, instruments variables, a method recently proposed by Lubotsky and Wittenberg, and a GMM estimator.
Abstract: Existing studies of the effects of college quality on wages typically rely on a single proxy variable for college quality. This study questions the wisdom of using a single proxy given that it likely contains substantial measurement error. We consider four econometric approaches to the problem that involve the use of multiple proxies for college quality: factor analysis, instruments variables, a method recently proposed by Lubotsky and Wittenberg, and a GMM estimator. Our estimates suggest that the existing literature understates the wage effects of college quality and illustrate the value of using multiple proxies in this and other similar contexts.
410 citations
Patent•
20 Apr 2006
TL;DR: In this article, a method for enabling access to a data resource, which is held on a file server ( 25 ) on a first local area network (LAN) (21 a ), by a client ( 28 ) on the second LAN (21 b ), is presented.
Abstract: A method for enabling access to a data resource, which is held on a file server ( 25 ) on a first local area network (LAN) ( 21 a ), by a client ( 28 ) on a second LAN ( 21 b ). A proxy receiver ( 48 ) on the second LAN ( 21 b ) intercepts a request for the data resource submitted by the client ( 28 ) and transmits a message via a wide area network (WAN) ( 29 ) to a proxy transmitter ( 52 ) on the first LAN ( 21 a ), requesting the data resource. The proxy transmitter ( 52 ) retrieves a replica of the data resource from the file server ( 25 ) and conveys the replica of the data resource over the WAN ( 29 ) to the proxy receiver ( 48 ), which serves the replica of the data resource from the proxy receiver ( 48 ) to the client ( 28 ) over the second LAN ( 21 b ).
383 citations
TL;DR: This article applied Haider and Solon's generalized errors-in-variables model to Swedish income tax data to produce estimates of the association between current and lifetime income, showing strong life cycle patterns.
Abstract: We apply Haider and Solon’s generalized errors‐in‐variables model to Swedish income tax data to produce estimates of the association between current and lifetime income. Our estimates demonstrate strong life‐cycle patterns. This implies that the widespread use of current income as a proxy for lifetime income leads to inconsistent parameter estimates (i.e., life‐cycle bias) even when the proxy is used as the dependent variable. Estimates for comparable cohorts of Swedish and American men demonstrate surprising similarities. There are, however, significant gender and cohort differences in this association that lead to statistically significant and quantitatively meaningful differences in life‐cycle biases.
319 citations
TL;DR: The authors showed that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility, and provided an additional argument for using the realized variance in out-of-sample evaluations rather than the squared return.
288 citations
TL;DR: Using patent citations as a proxy for the influence of foreign technology on French firms' patents, the authors found that the inventions of importers are significantly more likely to be influenced by foreign technology.
Abstract: Using patent citations as a proxy for the influence of foreign technology on French firms' patents, this paper finds that the inventions of importers are significantly more likely to be influenced ...
197 citations
TL;DR: The authors used a large panel data set for introductory microeconomics students to explicitly take into account the effect of unobservable factors correlated with attendance, such as ability, effort, and motivation.
Abstract: The author presents new evidence on the effects of attendance on academic performance. He used a large panel data set for introductory microeconomics students to explicitly take into account the effect of unobservable factors correlated with attendance, such as ability, effort, and motivation. He found that neither proxy variables nor instrumental variables provide a solution to the omitted variable bias. Panel estimators indicate that attendance has a smaller but significant impact on performance. Lecture and classes have a similar effect on performance individually, although their impact cannot be identified separately. Overall, the results indicate that, after controlling for unobservable student characteristics, attendance has a statistically significant and quantitatively relevant effect on student learning.
192 citations
TL;DR: A procedure by which the coefficient of interest can be extracted "post hoc" from a multiple regression in which all the proxies are used simultaneously, which is strictly superior in large samples to coefficients derived using any index or linear combination of the proxies that is created prior to the regression.
Abstract: Multiple proxy variables are typically available for an unobserved explanatory variable in a regression. We provide a procedure by which the coefficient of interest can be estimated from a regression in which all the proxies are included simultaneously. This estimator is superior in large samples to the common practice of creating a summary measure of the proxy variables. We examine the relationship between parents' income and children's reading test scores in the United States, and between parents' assets and children's school enrollment in India, and demonstrate that the reduction in attenuation bias from a better use of proxy variables can be significant.
133 citations
TL;DR: In this paper, the authors suggest a theoretical foundation to operationalize the constructs of spirituality from existing established measures, such as perceived organizational support, affective organizational commitment, and intrinsic job satisfaction.
Abstract: The purpose of this paper is to suggest a theoretical foundation to operationalize the constructs of spirituality from existing established measures. Several constructs from existing literature - perceived organizational support, affective organizational commitment, and intrinsic job satisfaction are used to measure aspects of workplace spirituality. As a result, a profile model of multidimensional constructs is used to explain the conceptual relationships.
133 citations
TL;DR: Significant differences between patient and proxy HRQL domain scores is modest at best and is affected by patient depression and proxy perception of burden, which may impact the outcome assessment in stroke clinical trials.
Abstract: Background and Purpose— Proxy respondents are often needed to report outcomes in stroke survivors, but they typically systematically rate impairments worse than patients themselves. The magnitude of this difference, the degree of agreement between patients and proxies, and the factors influencing agreement are not well known. Methods— We compared patient and family proxy health-related quality of life (HRQL) responses in 225 patient–proxy pairs enrolled in a clinical trial for poststroke depression. We used paired t-tests and the intraclass correlation (ICC) statistic to evaluate the agreement between patient and proxy domain scores and the overall Stroke-specific Quality of Life (SS-QOL) score. We used multivariate linear regression to model patient- and proxy-reported SS-QOL scores. Results— Patients were older (63 versus 55 years) and less often female (48% versus 74%) than proxies. Proxies rated all domains of SS-SQOL slightly worse than patients. The Mood, Energy, and Thinking domains had the greates...
TL;DR: For patient and proxy ratings, the EQ-5D had the best combination of measurement properties, although it had a substantial ceiling effect for patient ratings.
Abstract: Objectives: To explore whether Alzheimer’s disease patients could rate their quality of life (QOL) using utility-based health indexes, and to provide new knowledge about the measurement properties of these instruments for patient and caregiver proxy ratings. Methods: A convenience sample of 60 mild-moderate AD patients and their caregivers were randomized to complete the Quality of Well-Being Scale (QWB), Health Utilities Index (HUI3) or EQ-5D and visual analogue scale (VAS) on two occasions. Test–retest reliability (intraclass correlation coefficients) and convergent validity (Spearman correlations) of utility scores with global health status, activities of daily living, comorbidity, mood, cognition and other utility measures were assessed. Results: Completion time was shortest for the combined EQ-5D and VAS. For patients with mild dementia and for proxies, reliability was ≥ 0.70 for the EQ-5D, QWB and HUI3. The EQ-5D had a ceiling effect for patient ratings. Convergent validity was demonstrated for patient and proxy ratings, with the strongest validity for EQ-5D ratings and the weakest validity for HUI3 patient ratings. Mean patient utility scores were significantly higher than mean proxy scores for all measures (p<0.001). Conclusions: For patient and proxy ratings, the EQ-5D had the best combination of measurement properties, although it had a substantial ceiling effect for patient ratings. Proxy QOL ratings did not accurately reflect patients’ ratings.
Patent•
28 Nov 2006TL;DR: In this article, a server and a client are configured to trust a certificate of an intermediate proxy device, and the proxy device may intercept a client-server security session request message sent from the client to the server.
Abstract: In one embodiment, a server and a client are configured to trust a certificate of an intermediate proxy device. The proxy device may then intercept a client-server security session request message sent from the client to the server. In response, the proxy device initiates a proxy-server security session with the server and obtains server security information from the server. Then, the proxy device initiates a client-proxy security session with the client using the trusted proxy certificate, and obtains client security information from the client. Upon obtaining the client security information, the proxy device creates a dynamic certificate using the obtained client security information and the trusted proxy certificate, and establishes the initiated proxy-server security session with the dynamic certificate. The proxy device then establishes the initiated client-proxy session, wherein the client-proxy security session and proxy-server security session transparently appear to the client and server as the requested client-server security session.
TL;DR: In this paper, the authors adapt the measurement error consistent estimators in Erickson and Whited (2002) to estimate the extent to which variation in true unobservable q explains variation in different proxies for q.
Abstract: Tobin's q is widely accepted as a proxy for an underlying “true” q, which is assumed to characterize a firm's incentive to invest. Researchers have developed numerous methods for computing q. This article assesses the measurement quality of different proxies for q. We adapt the measurement-error consistent estimators in Erickson and Whited (2002) to estimate the extent to which variation in true unobservable q explains variation in different proxies for q. We find most proxies for q are poor: careful algorithms for calculating q do little to improve measurement quality. Using elaborate algorithms, however, depletes the number of usable observations and possibly introduces sample selection bias.
Patent•
07 Sep 2006
TL;DR: In this article, the authors present a call routing system for distributed VoIP networks where a host name, representing a proxy, is assigned to and associated with a device, and a DNS record for the host name is changed to specify the IP address of a second proxy.
Abstract: Methods and systems are provided for intelligent call routing through distributed VoIP networks. A host name, representing a proxy, is assigned to and associated with a device. An IP address of a first proxy is acquired via a DNS query for the host name. The quality of the connection between the first proxy and the device is measured at least in part by calculating the round-trip delay for messages between the first proxy and the device. A DNS record for the host name is changed to specify the IP address of a second proxy. The IP address of the second proxy is acquired via a second DNS query for the host name. The quality of the connection between the second proxy and the device is measured at least in part by calculating the round-trip delay for messages between the second proxy and the device. The quality of the first and second connections is compared, and the IP address of the proxy with the higher-quality connection is assigned to the DNS record.
Patent•
15 Jun 2006TL;DR: In this article, a method of controlling access to network services enables an authorized proxy client to access a service on behalf of a user by registering proxy authorization information with a trusted security server.
Abstract: A method of controlling access to network services enables an authorized proxy client to access a service on behalf of a user. To permit the client to function as a proxy, the user registers proxy authorization information with a trusted security server. The proxy authorization information identifies the proxy client and specifies the extent of proxy authority granted to the proxy client. When the proxy client wants to access a target service on behalf of the user, it sends a proxy request to the trusted security server. The trusted security server checks the proxy authorization information of the user to verify whether the request is within the proxy authority granted to the proxy client. If so, the trusted security server returns to the proxy client a data structure containing information recognizable by the target service to authenticate the proxy client for accessing the target service on behalf of the user.
TL;DR: In this paper, the authors compared two alternative techniques for the modelling of the determinants of sovereign ratings, specifically, ordered probit and case-based reasoning, and found that both approaches produce similar results in terms of which variables are significant and forecast accuracy.
Patent•
02 Feb 2006
TL;DR: In this article, the authors propose a proxy (e.g., a switch) that resides in a respective network environment between one or more clients and multiple servers, and the proxy facilitates a flow of data on the first connection and the set of second connections.
Abstract: A proxy (e.g., a switch) resides in a respective network environment between one or more clients and multiple servers. One purpose of the proxy is to provide the clients a unified view of a distributed file system having respective data stored amongst multiple remote and disparate storage locations over a network. Another purpose of the proxy is to enable the clients to retrieve data stored at the multiple servers. To establish a first connection between the proxy and a respective client, the proxy communicates with an authentication agent (residing at a location other than at the client) to verify a challenge response received from the client. When establishing a set of second connections with the multiple servers, the proxy communicates with the authentication agent to generate challenge responses on behalf of the client. The proxy facilitates a flow of data on the first connection and the set of second connections.
TL;DR: In this article, the authors derive necessary and sufficient conditions on functional form of the loss function for the ranking of competing volatility forecasts to be robust to the presence of noise in the volatility proxy, and derive some interesting special cases of this class of robust loss functions.
Abstract: The use of a conditionally unbiased, but imperfect, volatility proxy can lead to undesirable outcomes in standard methods for comparing conditional variance forecasts. We derive necessary and sufficient conditions on functional form of the loss function for the ranking of competing volatility forecasts to be robust to the presence of noise in the volatility proxy, and derive some interesting special cases of this class of "robust" loss functions. We motivate the theory with analytical results on the distortions caused by some widely-used loss functions, when used with standard volatility proxies such as squared returns, the intra-daily range or realised volatility. The methods are illustrated with an application to the volatility of returns on IBM over the period 1993 to 2003.
TL;DR: Adolescents, aged 13-17 years, can be used as a reliable source to assess the smoking status of their mothers and fathers, and parents, however, appeared to accurately identify the smokingstatus of their adolescent children less reliably.
Patent•
27 Dec 2006TL;DR: In this article, a method for generating a haptic penalty force, including in one embodiment, the steps of: defining a primary proxy position, defining a secondary proxy position; defining a HIP position, generating a first force in response to the primary proxy positions and the HIP position and generating a second force by using the secondary proxy positions as the haptic penalties.
Abstract: In one aspect, the invention relates to a method for generating a haptic penalty force, including in one embodiment, the steps of: defining a primary proxy position; defining a secondary proxy position; defining a HIP position; generating a first force in response to the primary proxy position and the HIP position and generating a second force in response to the secondary proxy position and the HIP position.
Patent•
17 Apr 2006
TL;DR: In this paper, a system and method for networked exchange is described, which consists of an internal proxy (140), an exchange processor (120), a database (130), an external proxy (150), and a communications network (110) connected to the external proxy.
Abstract: A system and method for networked exchange are disclosed. A system for networked exchange comprises an internal proxy (140); an exchange processor (120) in communication with the internal proxy (140); a database (130) in communication with the internal proxy (140); an external proxy (150) in communication with the internal proxy (140); and, a communications network (110) connected to the external proxy. A method for networked exchange comprises 8 steps. Those steps are (1) specifying a mode of operations for an exchange; (2) identifying a commodity for the exchange; (3) listing information about the commodity; (4) accessing of the listing by a potential purchaser; (5) accessing the network based exchange by the potential purchaser; (6) processing information generated by the potential purchaser, the information comprising a negotiation; (7) concluding the negotiation; and, (8) clearing the concluded negotiation.
13 Dec 2006
TL;DR: In this paper, the first proxy signature scheme without random oracle is proposed and the unforgeability of the scheme is based on the hardness of the well known Computational Diffie Hellman (CDH) problem.
Abstract: In mobile Ad Hoc networks, the existence and availability of trusted authorities is severely limited by intrinsic network features, and problems such as “service availability” have become a crucial issue. A proxy signature scheme allows an entity to delegate his/her signing capability to another entity in such a way that the latter can sign messages on behalf of the former when the former is not available. This is an important primitive to ensure the service availability issue. Proxy signatures have found numerous practical applications such as distributed systems, mobile agent applications, etc. However, the security of the known proxy signature schemes is proven in the random oracle which does not imply security in the real world. In this paper, we propose the first proxy signature schemes without random oracle. The unforgeability of our scheme is based on the hardness of the well known Computational Diffie Hellman (CDH) problem.
TL;DR: In this article, the impact of bank monitoring on loan contract terms using a new proxy for monitoring ability based on the labor input into monitoring was examined, and it was shown in out-of-sample tests that the proxy is a statistically and economically significant determinant of future loan quality.
Abstract: We examine the impact of bank monitoring on loan contract terms using a new proxy for monitoring ability based on the labor input into monitoring. We show in out-of-sample tests that the proxy is a statistically and economically significant determinant of future loan quality. Accounting for clustering of observations by lead bank, and controlling for borrower characteristics, contract features and bank risk, we find a statistically significant direct relationship between monitoring ability and loan maturity and a statistically and economically significant direct relationship between monitoring ability and the loan yield spread. The relationships are particularly strong for working capital loans.
TL;DR: In this paper, an efficient (t,n) threshold proxy signature scheme based on Schnorr's scheme is proposed that can reduce the amount of computations and communications and offer convenience and fair distribution of auditing a document's signers.
TL;DR: This paper showed that the bias actually is fairly small - less than 14% - when education effects on first birth timing are estimated from DHS surveys in sub-Saharan Africa, and that if other data are used or if the focus is turned to other independent variables than education the bias may of course be very different.
Abstract: There is much interest these days in the importance of community institutions and resources for individual mortality and fertility. DHS data may seem to be a valuable source for such multilevel analysis. For example researchers may consider including in their models the average education within the sample (cluster) of approximately 25 women interviewed in each primary sampling unit (PSU). However this is only a proxy for the theoretically more interesting average among all women in the PSU and in principle the estimated effect of the sample mean may differ markedly from the effect of the latter variable. Fortunately simulation experiments show that the bias actually is fairly small - less than 14% - when education effects on first birth timing are estimated from DHS surveys in sub-Saharan Africa. If other data are used or if the focus is turned to other independent variables than education the bias may of course be very different. In some situations it may be even smaller; in others it may be unacceptably large. That depends on the size of the clusters and on how the independent variables are distributed within and across communities. Some general advice is provided. (authors)
Patent•
21 Apr 2006TL;DR: In this article, a filtering proxy that includes one or more filters, classifiers, and/or detectors is used to monitor the input for code injection attacks, and a supervision framework can provide feedback to tune the components of the filtering proxy.
Abstract: In accordance with some embodiments of the present invention, systems and methods that protect an application from attacks are provided. In some embodiments of the present invention, input from an input source, such as traffic from a communication network, can be routed through a filtering proxy that includes one or more filters, classifiers, and/or detectors. In response to the input passing through the filtering proxy to the application, a supervision framework monitors the input for attacks (e.g., code injection attacks). The supervision framework can provide feedback to tune the components of the filtering proxy.
Patent•
18 Jan 2006
TL;DR: In this paper, a method and apparatus for enabling multiple application programs to control a system's physical resources by way of multiple resource proxies, while still enabling exclusive control of the physical resource by one application program is presented.
Abstract: A method and apparatus for enabling multiple application programs to control a system's physical resources by way of multiple resource proxies, while still enabling exclusive control of the physical resource by one application program. Control tokens are used to limit control to one proxy. The proxy having the control token is tracked in an access control list. Java API methods that can alter the state of a physical resource are marked with an access control attribute during grinding. A resource management module intercepts API methods attempting to obtain control of the physical resource. If a proxy controlled by the application program invoking the intercepted method has control the method is allowed to use the proxy to control the physical resource.
Patent•
02 May 2006TL;DR: In this paper, a dynamic syndicated content delivery system and method, the system having: a push proxy, the push proxy having a message store, the deferred retrieval message store adapted to storing deferred content for future delivery; a push agent, push agent adapted to push content; and a push scheduler, push schedule adapted to communicate with push agent to schedule the pushing of content and further adapted to monitor a wireless network for network conditions.
Abstract: A dynamic syndicated content delivery system and method, the system having: a push proxy, the push proxy having: a deferred retrieval message store, the deferred retrieval message store adapted to storing deferred content for future delivery; a push agent, the push agent adapted to push content; and a push scheduler, the push schedule adapted to communicate with the push agent to schedule the pushing of content and further adapted to monitor a wireless network for network conditions; a push client, the push client having: a client push agent, the client push agent adapted to communicate with the push agent of the push proxy; a content pull broker, the content pull broker adapted to communicate with the deferred retrieval message store of the push proxy; a deferred retrieval manager, the deferred retrieval manager adapted to communicate with the content pull broker and the client push agent to pull content, the deferred retrieval manager further adapted to monitor a network and instruct the content pull broker to pull the content if the network conditions are favorable for receiving the deferred content; and a network status monitor adapted to monitor the status of the network; and the wireless network.
TL;DR: In this paper, the authors investigated the role that economic variables play in the determination of happiness, using reported happiness as a proxy to individual well-being, and found that there is a positive and significant correlation between happiness and income.
Abstract: The empirical determinants of happiness in Brazil. This paper investigates the role that economic variables play in the determination of happiness, using reported happiness as a proxy to individual well-being. We use microdata extracted from the World Values Survey for five countries, emphasizing the Brazilian case. Our findings suggest that there is a positive and significant correlation between happiness and income. Unemployment is also a large source of unhappiness. In most cases, happiness appears to be positively correlated to being married. Moreover, hap