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Modeling interval-censored, clustered cow udder quarter infection times through the shared gamma frailty model

Klara Goethals UGent, Bart Ampe UGent, Dirk Berkvens UGent, Hans Laevens, Paul Janssens and Luc Duchateau UGent (2009) JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS. 14(1). p.1-14
abstract
Time to infection data are often simultaneously clustered and interval-censored. The time to infection is not known exactly; it is only known to have occurred within a certain interval. Moreover, observations often occur in clusters. Consequently, the independence assumption does not hold. Here we propose an extension of the shared gamma frailty model to handle the interval censoring and clustering simultaneously. We show that the frailties can be integrated out analytically, allowing maximization of the marginal likelihood to obtain parameter estimates. We apply our method to a longitudinal study with periodic follow-up on dairy cows to investigate the effect of parameters at the cow level (e.g., parity) and also parameters that can change within the cow (e.g., front or rear udder quarter) on time to infection. Dairy cows were assessed approximately monthly for the presence of a bacterial infection at the udder-quarter level, thus generating interval-censored data. Obviously, the four udder quarters are clustered within the cow. Based on simulations, we find that ignoring the interval-censored nature of the data can lead to biased parameter estimates.
Please use this url to cite or link to this publication:
author
organization
year
type
journalArticle (original)
publication status
published
subject
keyword
Interval censoring, CLINICAL MASTITIS, Mastitis, Multivariate survival data, PROPORTIONAL HAZARDS MODEL, Dairy cow, SOMATIC-CELL COUNT, BOVINE UDDER
journal title
JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS
J. Agric. Biol. Environ. Stat.
volume
14
issue
1
pages
1 - 14
Web of Science type
Article
Web of Science id
000265350000001
JCR category
STATISTICS & PROBABILITY
JCR impact factor
0.684 (2009)
JCR rank
70/100 (2009)
JCR quartile
3 (2009)
ISSN
1085-7117
DOI
10.1198/jabes.2009.0001
language
English
UGent publication?
yes
classification
A1
copyright statement
I have transferred the copyright for this publication to the publisher
id
701769
handle
http://hdl.handle.net/1854/LU-701769
date created
2009-06-16 13:56:30
date last changed
2011-12-23 10:37:29
@article{701769,
  abstract     = {Time to infection data are often simultaneously clustered and interval-censored. The time to infection is not known exactly; it is only known to have occurred within a certain interval. Moreover, observations often occur in clusters. Consequently, the independence assumption does not hold. Here we propose an extension of the shared gamma frailty model to handle the interval censoring and clustering simultaneously. We show that the frailties can be integrated out analytically, allowing maximization of the marginal likelihood to obtain parameter estimates. We apply our method to a longitudinal study with periodic follow-up on dairy cows to investigate the effect of parameters at the cow level (e.g., parity) and also parameters that can change within the cow (e.g., front or rear udder quarter) on time to infection. Dairy cows were assessed approximately monthly for the presence of a bacterial infection at the udder-quarter level, thus generating interval-censored data. Obviously, the four udder quarters are clustered within the cow. Based on simulations, we find that ignoring the interval-censored nature of the data can lead to biased parameter estimates.},
  author       = {Goethals, Klara and Ampe, Bart and Berkvens, Dirk and Laevens, Hans and Janssens, Paul and Duchateau, Luc},
  issn         = {1085-7117},
  journal      = {JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS},
  keyword      = {Interval censoring,CLINICAL MASTITIS,Mastitis,Multivariate survival data,PROPORTIONAL HAZARDS MODEL,Dairy cow,SOMATIC-CELL COUNT,BOVINE UDDER},
  language     = {eng},
  number       = {1},
  pages        = {1--14},
  title        = {Modeling interval-censored, clustered cow udder quarter infection times through the shared gamma frailty model},
  url          = {http://dx.doi.org/10.1198/jabes.2009.0001},
  volume       = {14},
  year         = {2009},
}

Chicago
Goethals, Klara, Bart Ampe, Dirk Berkvens, Hans Laevens, Paul Janssens, and Luc Duchateau. 2009. “Modeling Interval-censored, Clustered Cow Udder Quarter Infection Times Through the Shared Gamma Frailty Model.” Journal of Agricultural Biological and Environmental Statistics 14 (1): 1–14.
APA
Goethals, Klara, Ampe, B., Berkvens, D., Laevens, H., Janssens, P., & Duchateau, L. (2009). Modeling interval-censored, clustered cow udder quarter infection times through the shared gamma frailty model. JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS, 14(1), 1–14.
Vancouver
1.
Goethals K, Ampe B, Berkvens D, Laevens H, Janssens P, Duchateau L. Modeling interval-censored, clustered cow udder quarter infection times through the shared gamma frailty model. JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS. 2009;14(1):1–14.
MLA
Goethals, Klara, Bart Ampe, Dirk Berkvens, et al. “Modeling Interval-censored, Clustered Cow Udder Quarter Infection Times Through the Shared Gamma Frailty Model.” JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS 14.1 (2009): 1–14. Print.