is_ps_truncated() is an S3 generic that returns TRUE if its
argument represents a ps_trunc object or psw object created from
truncated propensity scores. is_ps_truncated() is a question about whether
the propensity scores have been truncated, as opposed to
is_unit_truncated(), which is a question about which units have been
truncated.
is_ps_truncated() is an S3 generic that returns TRUE if its argument represents a
ps_trunc object or psw object flagged as truncated.