Contains data from hpns\hpns.dta
  obs:             8                          hypothetical prenatal screening
                                                data; see ex3_1init.do
 vars:             4                          20 Jul 2005 18:14
 size:            96 (99.9% of memory free)
-------------------------------------------------------------------------------
              storage  display     value
variable name   type   format      label      variable label
-------------------------------------------------------------------------------
d               byte   %8.0g       ynlbl      disease
y               byte   %8.0g       testlbl    test outcome
nobs            int    %8.0g                  # of subjects
arm             long   %8.0g       armlbl   * Screening test
                                            * indicated variables have notes
-------------------------------------------------------------------------------
Sorted by:  

**********************
value labels for variables with numeric codes:

armlbl:
           1 EA
           2 CVS
testlbl:
           0 -
           1 +
ynlbl:
           0 no
           1 yes

*********************
notes:

arm:
  1.  unpaired data; randomization of subjects to 1 of 2 screening tests.
  2.  EA = early amniocentesis
  3.  CVS = chorionic villus sampling