Proportional hazards modeling of time-dependent covariates using linear regression
a case study
Document identifier: oai:DiVA.org:ltu-7776
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10.1109/24.536990Keyword: Engineering and Technology,
Civil Engineering,
Other Civil Engineering,
Teknik och teknologier,
Samhällsbyggnadsteknik,
Annan samhällsbyggnadsteknik,
Mining and Rock Engineering,
Gruv- och BerganläggningsteknikPublication year: 1996Relevant Sustainable Development Goals (SDGs):
The SDG label(s) above have been assigned by OSDG.aiAbstract: In the proportional hazards model, the effect of a covariate is assumed to be time-invariant. In this paper a graphical method based on a linear regression model (LRM) is used to test whether this assumption is realistic. The variation in the effect of a covariate is plotted against time. The slope of this plot indicates the nature of the influence of a covariate over time. A covariate is time-dependent if a drastic change in the slope of the plot is found and the time-point, at which this drastic change occurs provides guideline in redefining a time-dependent covariate into two or more time-independent covariates. This method is applied to failure data of cables used for supplying power to electric mine loaders. The results obtained by applying only the proportional hazards model were misleading as the graphical method based on the LRM showed that one covariate was highly time-dependent. This graphical method should be used to supplement the proportional hazards model, not as a separate method. This avoids misinterpretation of the influence of a time-dependent covariate in the proportional hazards model. The proportional hazards model should be used to identify the most important covariates, while the LRM should be used as an explanatory tool to check the consistency of the influence of the covariates. The LRM involves matrix computations which can be quite time consuming for large data-sets. Also, tests for the statistically significant effect of a covariate are not yet well established in the model
Authors
Dhananjay Kumar
Luleå tekniska universitet
Other publications
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Ulf Westberg
Luleå tekniska universitet
Other publications
>>
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identifier: oai:DiVA.org:ltu-7776
datestamp: 2021-04-19T13:02:01Z
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titleInfo:
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lang: eng
title: Proportional hazards modeling of time-dependent covariates using linear regression
subTitle: a case study
abstract: In the proportional hazards model the effect of a covariate is assumed to be time-invariant. In this paper a graphical method based on a linear regression model (LRM) is used to test whether this assumption is realistic. The variation in the effect of a covariate is plotted against time. The slope of this plot indicates the nature of the influence of a covariate over time. A covariate is time-dependent if a drastic change in the slope of the plot is found and the time-point at which this drastic change occurs provides guideline in redefining a time-dependent covariate into two or more time-independent covariates. This method is applied to failure data of cables used for supplying power to electric mine loaders. The results obtained by applying only the proportional hazards model were misleading as the graphical method based on the LRM showed that one covariate was highly time-dependent. This graphical method should be used to supplement the proportional hazards model not as a separate method. This avoids misinterpretation of the influence of a time-dependent covariate in the proportional hazards model. The proportional hazards model should be used to identify the most important covariates while the LRM should be used as an explanatory tool to check the consistency of the influence of the covariates. The LRM involves matrix computations which can be quite time consuming for large data-sets. Also tests for the statistically significant effect of a covariate are not yet well established in the model
subject:
@attributes:
lang: eng
authority: uka.se
topic:
Engineering and Technology
Civil Engineering
Other Civil Engineering
@attributes:
lang: swe
authority: uka.se
topic:
Teknik och teknologier
Samhällsbyggnadsteknik
Annan samhällsbyggnadsteknik
@attributes:
lang: eng
authority: ltu
topic: Mining and Rock Engineering
genre: Research subject
@attributes:
lang: swe
authority: ltu
topic: Gruv- och Berganläggningsteknik
genre: Research subject
language:
languageTerm: eng
genre:
publication/journal-article
ref
note:
Published
2
Godkänd; 1996; 20070503 (keni)
name:
@attributes:
type: personal
namePart:
Kumar
Dhananjay
role:
roleTerm: aut
affiliation: Luleå tekniska universitet
@attributes:
type: personal
namePart:
Westberg
Ulf
role:
roleTerm: aut
affiliation: Luleå tekniska universitet
originInfo:
dateIssued: 1996
relatedItem:
@attributes:
type: host
titleInfo:
title: IEEE Transactions on Reliability
identifier:
0018-9529
1558-1721
part:
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@attributes:
type: volume
number: 45
@attributes:
type: issue
number: 3
extent:
start: 386
end: 392
location:
url: http://ltu.diva-portal.org/smash/get/diva2:980666/FULLTEXT01.pdf
accessCondition: gratis
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typeOfResource: text