pFormula: An extended Formula interface for panel data

Description

pFormula is a Formula object used in the plm package.

Usage

pFormula(object)
## S3 method for class 'pFormula'
as.Formula(x, ...)

Arguments

Value

For pFormula, the return value is an object of class c("pFormula", "Formula", "formula").
For as.Formula, the return value is an object of class c("Formula", "formula").

Author(s)

Yves Croissant

See Also

plm's model.frame and model.matrix to create a model frame for panel data and a model matrix with data transformations applied, respectively.
plm's pmodel.response for (transformed) response variable.
Formula from package Formula.

Examples

# First, make a pdata.frame
data(Grunfeld)
pGrunfeld <- pdata.frame(Grunfeld)

# then make a model frame from a pFormula and a pdata.frame
pform <- pFormula(inv ~ value + capital)
mf <- model.frame(pform, data = pGrunfeld)

# then construct the (transformed) model matrix (design matrix)
# from formula and model frame
modmat <- model.matrix(pform, data = mf, model = "within")