Biomedical Engineering Reference
In-Depth Information
models only apply to limited situations and a lot of more work is needed for
the problem.
1.6
Analysis
of
Multivariate
or
Clustered
Interval-
Censored Data
So far the discussion has focused on independent or univariate interval-
censored data. In other words, it has been assumed that there exists only
one failure time variable of interest and all samples are independent of each
other. Sometimes the failure times of interest are clustered into small groups
or some study subjects are related, such as siblings, families, or communi-
ties. The subjects from the same cluster or group usually share certain unob-
served characteristics and their failure times tend to be correlated as a result.
Siblings, for example, share the same genetic and environmental influences
(Jonker et al. (2009)). In other words, for such data, the failure times within
the same cluster are dependent, while the failure times from different clus-
ters can be regarded as independent. With the existence of interval-censoring,
such failure time data are commonly referred to as clustered interval-censored
data. It is apparent that for the analysis of such data, one needs different
inference procedures than those discussed above, and one key and important
feature of these different procedures is that they need to take into account the
correlation among the failure time variables.
A related and special case of clustered interval-censored data is multi-
variate interval-censored data, which arise if a survival study involves several
related failure time variables of interest and they may suffer interval-censoring.
In this case, the related failure times can be seen a cluster and we have clus-
tered interval-censored data with the same cluster sizes, while for general clus-
tered data, the cluster size could differ from one to another. For the analysis
 
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