我用winsteps 计算了Fox, C. M., & Bond, T. G. (2001). Applying the Rasch model :fundamental measurement in the human sciences . Mahwah, N.J. : LawrenceErlbaum Associates, Publishers.书中p56 页上的Table 5.1 中的结果，利用本书的伴读网站中的数据，见附件，我发现计算结果和56页上的计算结果有出入。但不是很大，请问这是什么原因？谢谢。
我的计算结果

ITEMPRTIII for Chapter FiveMar 30
;ENTRY MEASURE STTS COUNT SCOREERROR IN.MSQ IN.ZSTD OUT.MS OUT.ZSTD DISPL PTME WEIGHT OBSMA EXPMADISCR G M NAME
1 -3.431 143.0 127.0 .30 1.25 1.35 1.08 .33 .00 .44 1.0086.089.5 .79 1 R Item 1
2 3.671 143.0 6.0 .44 .91 -.16 .64 .05 .00 .34 1.0096.595.8 1.05 1 R Item 2
3 .861 143.0 41.0 .22 1.17 1.48 1.09 .40 .00 .47 1.0074.179.4 .78 1 R Item 13
4 -.661 143.0 75.0 .21 .94 -.58 .98 -.04 .00 .61 1.0081.176.3 1.07 1 R I0004
5 -.401 143.0 69.0 .21 .93 -.72 .90 -.51 .00 .62 1.0081.176.5 1.11 1 R I0005
6 1.021 143.0 38.0 .23 1.17 1.47 1.29 .98 .00 .45 1.0076.280.0 .75 1 R I0006
7 -.831 143.0 79.0 .21 .82-1.82 .75-1.40 .00 .67 1.0081.876.4 1.29 1 R I0007
8 -3.031 143.0 122.0 .27 1.09 .64 2.98 2.65 .00 .48 1.0088.186.7 .83 1 R I0008
9 .581 143.0 47.0 .22 1.04 .40 1.30 1.20 .00 .52 1.0079.778.5 .88 1 R I0009
10 -.871 143.0 80.0 .21 1.00 .03 .86 -.73 .00 .61 1.0075.576.5 1.04 1 R I0010
11 .721 143.0 44.0 .22 .85-1.43 .72-1.09 .00 .60 1.0084.678.8 1.22 1 R I0011
12 -.441 143.0 70.0 .21 .97 -.29 .83 -.96 .00 .61 1.0073.476.5 1.09 1 R I0012
13 2.811 143.0 12.0 .33 .78 -.97 .66 -.24 .00 .45 1.0092.391.9 1.15 1 R I0013