epidataCS_permute {surveillance}

Randomly Permute Time Points or Locations of "epidataCS"

Description

Monte Carlo tests for space-time interaction (epitest) use the distribution of some test statistic under the null hypothesis of no space-time interaction. For this purpose, the function permute.epidataCS randomly permutes the time or space labels of the events.

Usage

permute.epidataCS(x, what = c("time", "space"), keep)

Arguments

x

an object of class "epidataCS".

what

character string determining what to permute: time points (default) or locations.

keep

optional logical expression to be evaluated in the context of x$events@data, determining for which events the time and location should be kept as is. For instance, to keep some “prehistory” before time point 30 unchanged, use keep = time <= 30.

Value

the permuted "epidataCS" object.

Author(s)

Sebastian Meyer

See Also

epitest

Examples

data("imdepi")

set.seed(3)
permepi <- permute.epidataCS(imdepi, what = "time", keep = time <= 30)

print(imdepi, n = 8)
print(permepi, n = 8)
## the first 6 events are kept (as are all row.names),
## the time labels of the remaining events are shuffled
## (and events then again sorted by time),
## the marginal temporal distribution is unchanged