User Guide for the TIMSS International Database.pdf - TIMSS and ...

C H A P T E R 9 P E R F O R M I N G A N A L Y S E S
9.3.2 SPSS Macro for Computing Mean and Percents with
Corresponding Standard Errors (JACK.SPS)
The CD containing the TIMSS International Database also contains an SPSS macro program
called JACK.SPS. This macro can be used to compute weighted percents and means within
categories. Although the user can compute weighted percent and mean estimates using other
basic SPSS commands, the macro JACK.SPS also computes the JRR error estimate for these
means and percents. The control code for the macro JACK.SPS is presented in Figure 9.7.
Figure 9.7
SPSS Macro for Computing Mean and Percents with Corresponding JRR Standard
Errors (JACK.SPS)
set mprint=on.
define jack (cvar = !charend('/') /
dvar = !charend('/') /
njkr = !charend('/') /
jkz = !charend('/') /
jki = !charend('/') /
wgt = !charend('/') ) .
weight off.
sort cases by !cvar .
compute k = 1.
compute wgtx = !wgt * !dvar.
vector rwgt(!njkr).
vector rwgtx(!njkr).
loop #i = 1 to !njkr.
if (!jkz = #i and !jki = 0) rwgt(#i) = !wgt * 0.
if (!jkz = #i and !jki = 1) rwgt(#i) = !wgt * 2.
if (!jkz #i ) rwgt(#i) = !wgt * 1.
compute rwgtx(#i) = rwgt(#i) * !dvar.
end loop.
!let !nway = tmpjck1
aggregate outfile = !nway
/ presorted
/ break = !cvar k
/ !wgt rwgt1 to !concat(rwgt,!njkr) wgtx rwgtx1 to !concat(rwgtx,!njkr)
= sum(!wgt rwgt1 to !concat(rwgt,!njkr) wgtx rwgtx1 to !concat(rwgtx,!njkr))
/ n = n(!wgt).
!let !cvar1 = !null
!do !i !in(!cvar)
!let !cvar1 = !concat(!i,!blank(1),!cvar1)
!doend
!let !cvar2a = !concat(!cvar1,!blank(1),k)
!let !cvar2b = !concat(!tail(!cvar1),!blank(1),k)
!do !i !in(!cvar2a)
!if (!cvar2b = !null) !then !break
!ifend
get file = !nway.
compute k = 1.
!let !seq = !index(!cvar1,!i)
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