Variance estimation of the expected number of deaths

Description

This function estimates the variance of the expected number of deaths when the latter is estimated using Sasieni's method.

Usage

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var.expDeath(contribution, incid, cox, fuzz, Poisson = FALSE, covnames)

Arguments

contribution

An object of contributions produced by the function contrib.

incid

A matrix containing: the incidences, the value of the covariates and the person-years at risk, in that order. It can be obtained with the function incidences.

cox

An oject of class coxph containing the model that was used to estimate the survival in the cohort of non-participants.

fuzz

Numerical precision is problematic when it comes to test equality between objects. The option fuzz is used to consider objects not differing by more then fuzz to be equal. The fuzz option should be chosen to be a small positive number, for instance 0.0001.

covnames

An alphanumeric vector containing the names of the covariates used to estimate the survival in the cohort of non-participants, that is, the names of the covariates used to obtain the cox object.

Poisson

Indicates whether the incidences' variance should be estimated with a Poisson distribution (TRUE) or a binomial distribution (FALSE). The default is FALSE.

Value

The function returns the variance of the expected number of deaths

Note

A complete example of how to use this function is available in the help page of the screening dataset.

Author(s)

Denis Talbot, Thierry Duchesne, Jacques Brisson, Nathalie Vandal.

References

Talbot, D., Duchesne, T., Brisson, J., Vandal, N. (2011) Variance estimation and confidence intervals for the standardized mortality ratio with application to the assessment of a cancer screening program, Statistics in Medicine, 30, 3024-3037.

See Also

est.expDeath, inference.SMR, screening

Examples

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#This example uses pre-built objects and shows the simple usage
#of the est.expDeath function when those objects already exists.
#For an example of how to built those object, refer to the 
#help page of the screening dataset.

#Remove "#" to run example. The function can be quite long (a few hours) to run:
#data(req.objects);
#cox.data = req.objects$cox.data;
#var.expDeath(req.objects$contribution,req.objects$incid,req.objects$cox,fuzz = 0.01, 
#req.objects$covnames);


#[1,] 39.31382