# 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

1 | ```
var.expDeath(contribution, incid, cox, fuzz, Poisson = FALSE, covnames)
``` |

### Arguments

`contribution` |
An object of contributions produced by the function |

`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 |

`cox` |
An oject of class |

`fuzz` |
Numerical precision is problematic when it comes to test equality between objects. The option |

`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 |

`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

1 2 3 4 5 6 7 8 9 10 11 12 13 | ```
#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
``` |