makeStratObj: Making a strat.elec.data Object from an elec.data Object
In elec.strat: Functions for election audits using stratified random samples

Description Usage Arguments Details Author(s) See Also Examples

Makes a strat.elec.data object from an elec.data object.

1	makeStratObj(Z, strat.col = NULL, CID = NULL, auditTable = NULL)

`Z`	An `elec.data` object.
`strat.col`	Name of column in `Z$V` that identifies strata. If no value of strat.col is passed, `makeStratObj` will assume that stratum ID is contained in `Z$V$CID`.
`CID`	A vector of length `nrow(Z$V)` that identifies strata.
`auditTable`	A `data.frame` of dimension `length(unique(CID)` x 2 used to identify the number of samples taken from each stratum. Including `auditTable` is not necessary if `Z` contains audit information.

makeStratObj requires as input a valid elec.data object Z such that one of the following is true:

Z has a vector Z$V$CID that identifies strata.
A strat.col name identifying the stratification column in Z$V is passed to makeStratObj.
A CID vector of length nrow(Z$V) specifying the stratification is passed to makeStratObj.

If Z$audit is NULL, information giving the number of sampled batches in each stratum can be included through auditTable. The argument auditTable should be a data.frame of dimensions unique(CID) x 2. The first column is a list of unique stratum IDs. The second column is the number of batches sampled within the corresponding stratum.

makeStratObj creates a data.frame Z$strat. The columns of Z$strat are

CID The ID of the stratum.
CIDnum A number between 1 and length(Z$strat$CID) assigned to that stratum.
n The number of batches contained in that stratum.
audit The number of batches sampled from that stratum.

If no audit data is provided, Z$strat$audit defaults to a zero vector.

If Z$V$CID is NULL, makeStratObj will copy the stratum labels into Z$V$CID. makeStratObj will also create

Z$CID.col"CID"
Z$CIDnum The CIDnum of the stratum.
Z$V$e.max maximumMarginBound(Z)

If Z$audit[Z$PID.col] is not NULL, makeStratObj will create Z$audit$e.max, the maximumMarginBound(Z) for batches in Z$audit.

After sending an elec.data object through makeStratObj, the object will be both an elec.data object and a strat.elec.data object.

Mike Higgins, Hua Yang

See strat.elec.data to create a strat.elec.data object from a votes data.frame and an audit data.frame.

	data("CA_House_2008")
	dstrat <- CA_House_2008.strat[[1]]
	auditTable <- cbind(unique(dstrat$V$CID),1)
	dstrat <- makeStratObj(dstrat,auditTable = auditTable)