Title  'Combining data from zygosity, 14, 20, & 24 month files'.
Subtitle 'Creating a combined Home Shyness file'.
*
*  First, convert each of the portable files into a system file
*        Each of the four portable files has been downloaded from
*        data entry system.  Keep in each file only the variables needed.
*
import file = 'zygos.por'.
save outfile = 't0.sys'.
import file = 'MALTS14.por'/keep=twinid,v1hshypc.
save outfile = 't14.sys'.
import file = 'MALTS20.por'/keep=twinid,v2hshypc.
save outfile = 't20.sys'.
import file = 'MALTS24.por'/keep=twinid,y2hshypc.
save outfile = 't24.sys'.
*
*  Match the files together, using TWINID as the linking variable
*
match files file = 't0.sys'/file='t14.sys'/file='t20.sys'/
            file = 't24.sys'/by twinid.
disp labels.
*
*  Identify means for the Home Shyness composites by different zygosities
*
means tables = v1hshypc,v2hshypc,y2hshypc by zygos.
*
*  Look at longitudinal stability for the Home Shyness composite
*
corr  v1hshypc,v2hshypc,y2hshypc.
*
*  Export a file with the combined variables
*
export outfile = 'merge.por'/keep=twinid,family,twin,sex,zygos,
                                  v1hshypc,v2hshypc,y2hshypc.