Extend a longitudinal model.
This method increases the sample size for a model.
extend(object, along, within, n, values)
object |
a fitted model object to extend. |
along |
the name of an explanatory variable. This variable will have its number of levels extended. |
within |
names of grouping variables, separated by "+" or ",". Each combination of groups will be
extended to |
n |
number of levels: the levels of the explanatory variable will be replaced by |
values |
alternatively, you can specify a new set of levels for the explanatory variable. |
extend takes "slices" through the data for each unique value of the extended variable.
An extended dataset is built from n slices, with slices duplicated if necessary.
A copy of object suitable for doSim with an extended dataset attached as
an attribute named newData.
fm <- lmer(y ~ x + (1|g), data=simdata) nrow(example) fmx1 <- extend(fm, along="x", n=20) nrow(getData(fmx1)) fmx2 <- extend(fm, along="x", values=c(1,2,4,8,16)) nrow(getData(fmx2))
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