withReplicates {survey} | R Documentation |

## Compute variances by replicate weighting

### Description

Given a function or expression computing a statistic based on sampling
weights, `withReplicates`

evaluates the statistic and produces a
replicate-based estimate of variance.

### Usage

withReplicates(design, theta, rho = NULL, ..., scale.weights=FALSE, return.replicates=FALSE)

### Arguments

`design` |
A survey design with replicate weights (eg from `svrepdesign` ) |

`theta` |
A function or expression: see Details below |

`rho` |
If `design` uses BRR weights, `rho` optionally
specifies the parameter for Fay's variance estimator. |

`...` |
Other arguments to `theta` |

`scale.weights` |
Divide the probability weights by their sum (can
help with overflow problems) |

`return.replicates` |
Return the replicate estimates as well as
the variance? |

### Details

If `theta`

is a function its first argument will be a vector of
weights and the second argument will be a data frame containing the
variables from the design object.

If it is an expression, the sampling weights will be available as the
variable `.weights`

. Variables in the design object will also
be in scope. It is possible to use global variables in the
expression, but unwise, as they may be masked by local variables
inside `withReplicates`

.

### Value

If `return.replicates=FALSE`

, the weighted statistic, with the
variance matrix as the `"var"`

attribute. If
`return.replicates=TRUE`

, a list with elements `theta`

for
the usual return value and `replicates`

for the replicates.

### See Also

`svrepdesign`

, `as.svrepdesign`

, `svrVar`

### Examples

data(scd)
repweights<-2*cbind(c(1,0,1,0,1,0), c(1,0,0,1,0,1), c(0,1,1,0,0,1),
c(0,1,0,1,1,0))
scdrep<-svrepdesign(data=scd, type="BRR", repweights=repweights)
a<-svyratio(~alive, ~arrests, design=scdrep)
print(a$ratio)
print(a$var)
withReplicates(scdrep, quote(sum(.weights*alive)/sum(.weights*arrests)))
withReplicates(scdrep, function(w,data) sum(w*data$alive)/sum(w*data$arrests))

[Package

*survey* version 3.18

Index]