AN EXAMPLE FOR THE DFITD4 PROGRAM for o scale FOCAL GROUP ITEM PARAMETERS 1 .259 -1.015 .206 2 .719 -.552 .103 3 .645 -.627 .098 4 .467 .045 .280 5 .461 -2.468 .193 6 .469 -2.113 .171 7 .500 .986 .155 8 .597 -.769 .124 9 .641 -.694 .053 10 .492 .132 .272 11 .612 -1.116 .199 12 .497 .266 .070 13 .527 .611 .050 14 .377 .804 .096 15 .202 1.728 .185 16 .842 -1.362 .299 17 .666 .500 .132 18 1.101 -.136 .394 19 .393 -.500 .186 20 .257 .049 .220 21 .411 .254 .104 22 .377 1.288 .201 23 .231 1.426 .240 24 .843 -1.083 .132 25 .623 -1.472 .124 26 .282 -.710 .183 27 .737 .544 .135 28 .962 .384 .500 29 .683 -.179 .225 30 .632 -1.113 .210 REFERENCE GROUP ITEM PARAMETERS 1 .256 -.516 .201 2 .742 -.233 .120 3 .658 -.374 .055 4 .489 .100 .212 5 .523 -2.038 .192 6 .421 -2.102 .179 7 .516 1.061 .107 8 .675 -.268 .148 9 .627 -.161 .075 10 .534 .287 .290 11 .689 -.594 .239 12 .540 .928 .064 13 .501 1.224 .070 14 .393 1.489 .143 15 .262 2.242 .247 16 .847 -1.218 .280 17 .683 .629 .142 18 1.145 .034 .363 19 .400 -.023 .188 20 .265 .307 .187 21 .433 .572 .090 22 .478 1.909 .276 23 .338 2.149 .291 24 .797 -.706 .149 25 .600 -1.110 .166 26 .240 -.375 .203 27 .695 .808 .090 28 .908 .392 .500 29 .777 .140 .260 30 .684 -.680 .170 NUMBER OF CASES: 2499, D = 1.0, CRT = .006, A = 1.031, B = -.348 ITEM M-d SD-d M-ldl SD-ldl C(d,D) C-DIF NC-DIF CHI PROB ---- --- ---- ----- ------ ------ ----- ------ --- ---- 1 .011 .001 .011 .001 .000 -.000 .000 136177.80 .0000 2 -.012 .003 .012 .003 .000 .000 .000 44222.58 .0000 3 .004 .004 .004 .004 .000 .000 .000 4839.02 .0000 4 .008 .008 .008 .008 .000 -.000 .000 4762.62 .0000 5 -.014 .004 .014 .003 .000 .000 .000 38290.78 .0000 6 -.008 .010 .010 .009 .000 .000 .000 4039.79 .0000 7 .004 .007 .006 .006 .000 .000 .000 3359.05 .0000 8 .000 .007 .006 .004 .000 .000 .000 2502.70 .4697 9 .019 .007 .019 .006 .000 -.000 .000 20240.73 .0000 10 -.025 .002 .025 .002 .000 .000 .001 341649.80 .0000 11 -.007 .004 .007 .004 .000 .000 .000 10112.81 .0000 12 .044 .004 .044 .004 .000 -.001 .002 254416.20 .0000 13 .017 .012 .018 .010 .000 -.000 .000 7614.33 .0000 14 .004 .005 .005 .003 .000 .000 .000 3671.59 .0000 15 -.010 .004 .010 .004 .000 .000 .000 15952.32 .0000 16 -.015 .006 .015 .006 .000 .000 .000 17575.66 .0000 17 -.032 .003 .032 .003 .000 .000 .001 370900.50 .0000 18 -.012 .008 .014 .005 .000 .000 .000 7710.47 .0000 19 .010 .001 .010 .001 .000 -.000 .000 320236.10 .0000 20 .012 .002 .012 .002 .000 -.000 .000 104373.20 .0000 21 .006 .003 .006 .003 .000 .000 .000 13534.42 .0000 22 -.006 .003 .006 .003 .000 .000 .000 10976.77 .0000 23 .015 .009 .015 .008 .000 -.000 .000 9696.61 .0000 24 .007 .010 .011 .005 .000 -.000 .000 3645.76 .0000 25 -.005 .010 .007 .008 .000 .000 .000 3084.20 .0000 26 -.002 .010 .008 .006 .000 .000 .000 2638.30 .0251 27 .013 .003 .013 .003 .000 -.000 .000 49416.77 .0000 28 -.033 .007 .033 .007 .000 .001 .001 55149.66 .0000 29 -.022 .004 .022 .004 .000 .000 .001 66495.89 .0000 30 .015 .010 .015 .010 .000 -.000 .000 8226.61 .0000 TRUE-F TRUE-R D C-DIF lDl ------ ------ - ----- --- MEAN 19.026 19.041 -.01492 .00001 .01492 VARIANCE 7.045 7.038 .00003 .00000 .00003 STD. DEV. 2.654 2.653 .00570 .00025 .00570 CORRELATION BETWEEN FOCAL AND REFERENCE TRUE SCORES: 1.00000 DIFFERENTIAL TEST FUNCTIONING (DTF): .00026 SQURE-ROOT OF DTF: .01597 SD OF D**2: .00015 CHI-SQUARE VALUE: 19648.97 PROB: .0000 DEGREES OF FREEDOM CHI-SQAURE: 2498 ITEM DELETION PROCEDURE A RUN ITEM REMOVED DTF CHI-SQUARE PROB MEAN D MEAN lDl --- ----------- --- ---------- ---- ------ -------- 1 NONE .00026 19648.97 .000 -.01492 .01492