Synthesizes one variable (y) from another one (x)
when y is nested in the categories of x. A bootstrap
sample is created from the original values of y within each category
of xp (the synthesised values of the grouping variable).
syn.nested(y, x, xp, smoothing = "", cont.na = NA, ...)A list with two components:
a vector of length k with synthetic values of y.
a name of the method used for synthesis ("nested").
an original data vector of length n for the nested variable.
an original data vector of length n for the variable within
which y is nested.
a vector of length k with synthetic values of x.
smoothing method. See syn.smooth.
when y is numeric this can be a list or a vector giving values
of y that indicate missing values.
additional parameters.
An example would be when x is a classification
of occupations and y is a more detailed sub-classification. It is
intended that x is a categorical (factor) variable.
A warning will be issued if the original y is not nested within x.
A variable synthesised by syn.nested() is automatically excluded from
predicting later variables because it will provide no extra information,
given its grouping variable.
syn.nested() is also used for the final synthesis of variables in
syn() when the option numtocat is used to synthesise numerical
variables as groups.