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Proxy (statistics)

About: Proxy (statistics) is a research topic. Over the lifetime, 5257 publications have been published within this topic receiving 94504 citations. The topic is also known as: proxy variable & proxy measurement.


Papers
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Journal ArticleDOI
TL;DR: The formula for estimating an individual's life span given the frailty index value is presented and it is proposed that it may be used as a proxy measure of aging.
Abstract: This paper develops a method for appraising health status in elderly people. A frailty index was defined as the proportion of accumulated deficits (symptoms, signs, functional impairments, and laboratory abnormalities). It serves as an individual state variable, reflecting severity of illness and proximity to death. In a representative database of elderly Canadians we found that deficits accumulated at 3% per year, and show a gamma distribution, typical for systems with redundant components that can be used in case of failure of a given subsystem. Of note, the slope of the index is insensitive to the individual nature of the deficits, and serves as an important prognostic factor for life expectancy. The formula for estimating an individual's life span given the frailty index value is presented. For different patterns of cognitive impairments the average within-group index value increases with the severity of the cognitive impairment, and the relative variability of the index is significantly reduced. Finally, the statistical distribution of the frailty index sharply differs between well groups (gamma distribution) and morbid groups (normal distribution). This pattern reflects an increase in uncompensated deficits in impaired organisms, which would lead to illness of various etiologies, and ultimately to increased mortality. The accumulation of deficits is as an example of a macroscopic variable, i.e., one that reflects general properties of aging at the level of the whole organism rather than any given functional deficiency. In consequence, we propose that it may be used as a proxy measure of aging.

1,900 citations

Journal ArticleDOI
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

Book ChapterDOI
31 May 1998
TL;DR: A definition of protocol divertibility is given that applies to arbitrary 2-party protocols and is compatible with Okamoto and Ohta's definition in the case of interactive zero-knowledge proofs and generalizes to cover several protocols not normally associated with divertibility.
Abstract: First, we introduce the notion of divertibility as a protocol property as opposed to the existing notion as a language property (see Okamoto, Ohta [OO90]) We give a definition of protocol divertibility that applies to arbitrary 2-party protocols and is compatible with Okamoto and Ohta's definition in the case of interactive zero-knowledge proofs Other important examples falling under the new definition are blind signature protocols We propose a sufficiency criterion for divertibility that is satisfied by many existing protocols and which, surprisingly, generalizes to cover several protocols not normally associated with divertibility (eg, Diffie-Hellman key exchange) Next, we introduce atomic proxy cryptography, in which an atomic proxy function, in conjunction with a public proxy key, converts ciphertexts (messages or signatures) for one key into ciphertexts for another Proxy keys, once generated, may be made public and proxy functions applied in untrusted environments We present atomic proxy functions for discrete-log-based encryption, identification, and signature schemes It is not clear whether atomic proxy functions exist in general for all public-key cryptosystems Finally, we discuss the relationship between divertibility and proxy cryptography

1,533 citations

Journal ArticleDOI
John Pound1
TL;DR: In this article, three problems may discourage the use of proxy contests to challenge management and transfer corporate control: inefficiency in the system of proxy vote solicitation can give management a vote-getting advantage, institutional investors may vote with management against their own fiduciary interests, and some dissident proxy challenges may be "crank" bids with no prospect for increasing share values.

1,073 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show how proxy variable approaches to control for unobserved productivity, proposed by Olley and Pakes, can be implemented by specifying different instruments for different equations and applying generalized method of moments.

1,042 citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,242
20222,473
2021334
2020262
2019250
2018282