should an extended result be given or a
single p-value.
...
extra agruments
Value
either a single value (extended=FALSE)
representing the p-value of the test or a single row.
data.frame object that also incldues extra
information such as
Details
This is a generic helper function for extracting p values
from objects. The idea being to extract the overall
p-value for the model that can be interpreted simply.