In this example, responses
to 50 items are read from those of 100 items in the data file
using the format statement
The first few lines of
the data file are shown below. Each position in the item response
fields for each examinee corresponds to the same item. In
other examples, the association between response and item
may depend on the group/form membership of an examinee.
The
answer key (KFNAME keyword on the INPUT command) is given first, and is given
in the first two lines of the raw data file in the same format as the item
responses.
From the 50, 20 are selected as Main Test
items and 4 as Variant Test items. This is indicated by setting
NITEM to 24 and NVARIANT to 4 on the LENGTH command. Items
for the main test are selected by name in the TESTM
command; items for the variant test are selected by name in
the TESTV command. The item names correspond to the sequence
numbers in the original set of 100 items. Here the short form
of naming and numbering is used - the set of items forms an
arithmetic progression of integer or decimal numbers allowing
use of the short form (first (increment) last). A similar
abbreviation may be used for consecutive item names (INAME
keyword on the ITEMS command).
The
analysis is performed on a sample of 200 students randomly drawn from the
original sample of 660 (SAMPLE=200 on the INPUT command). The EAP scale scores
of Phase 3 are computed from the responses to items in the main test.
>ITEMS INUMBERS=(1(1)50), INAME=(I26(1)I75);
TEST
SPECIFICATIONS
===================
>TESTM TNAME=MAINTEST,
INAMES=(I26,I27,I28,I29,I31,I33,I34,
I35,I36,I38,I39,I47,I48,I49,I50,I54,I60,I64,I68,I72);
TEST NUMBER: 1
TEST NAME: MAINTEST
NUMBER OF ITEMS: 20
ITEM ITEM
ITEM ITEM ITEM
ITEM ITEM ITEM
NUMBER NAME
NUMBER NAME NUMBER
NAME NUMBER NAME
-----------------------------------------------------------------------
1 I26
9 I34 23
I48 43 I68
2 I27
10 I35 24
I49 47 I72
3 I28
11 I36 25
I50
4 I29
13 I38 29
I54
6 I31
14 I39 35
I60
8 I33
22 I47 39
I64
-----------------------------------------------------------------------
>TESTV TNAME=VARIANT,
INAMES=(I53,I59,I69,I73);
TEST NUMBER: 2
TEST NAME: VARIANT
NUMBER OF ITEMS: 4
ITEM ITEM
ITEM ITEM ITEM
ITEM ITEM ITEM
NUMBER NAME
NUMBER NAME NUMBER
NAME NUMBER NAME
-----------------------------------------------------------------------
28 I53
34 I59 44
I69 48 I73
-----------------------------------------------------------------------
Responses of 660 examinees
are read from the data records, but only 200 randomly sampled
cases are included in the Phase 1 and Phase 2 analysis. The
classical item statistics are shown separately for main and
variant items. The test scores for the item-test correlations
are based on the test scores from the main test items only.
660
OBSERVATIONS READ FROM FILE:
EXAMPL06.DAT
660 OBSERVATIONS WRITTEN TO
FILE: MF.DAT
REPORT ON SUBJECT SAMPLING:
LEVEL OF SAMPLING
= 0.3030
660 SUBJECTS
READ FROM FILE: MF.DAT
200 SUBJECTS WRITTEN TO FILE: CF.DAT
ITEM STATISTICS
FOR SUBTEST MAINTEST
ITEM*TEST CORRELATION
ITEM NAME #TRIED #RIGHT
PCT LOGIT/1.7 PEARSON
BISERIAL
------------------------------------------------------------------------
1
I26 200.0 134.0
67.0 -0.42 0.188
0.244
2
I27 200.0 102.0
51.0 -0.02 0.421
0.527
3
I28 200.0 78.0
39.0 0.26 0.294
0.374
4
I29 200.0 147.0
73.5 -0.60 0.444
0.598
5
I31 200.0 29.0
14.5 1.04 0.096
0.148
6
I33 200.0 97.0
48.5 0.04 0.246
0.309
7
I34 200.0 99.0
49.5 0.01 0.418
0.524
8
I35 200.0
31.0 15.5 1.00
0.282 0.428
9
I36 200.0 141.0
70.5 -0.51 0.212
0.280
10
I38 200.0 139.0
69.5 -0.48 0.289
0.380
11
I39 200.0 133.0
66.5 -0.40 0.521
0.675
12
I47 200.0 74.0
37.0 0.31 0.289
0.369
13
I48 200.0 100.0
50.0 0.00 0.497
0.623
14
I49 200.0 84.0
42.0 0.19 0.490
0.618
15
I50 200.0 91.0
45.5 0.11 0.429
0.539
16
I54 200.0 77.0
38.5 0.28 0.440
0.561
17
I60 200.0 32.0
16.0 0.98 0.245
0.369
18
I64 200.0 100.0
50.0 0.00 0.146
0.183
19
I68 200.0 160.0
80.0 -0.82 0.312
0.446
20
I72 200.0 99.0
49.5 0.01 0.418
0.524
------------------------------------------------------------------------
ITEM STATISTICS
FOR SUBTEST VARIANT
ITEM*TEST
CORRELATION
ITEM NAME #TRIED #RIGHT PCT
LOGIT/1.7 PEARSON BISERIAL
-------------------------------------------------------------------------
1
I53 200.0 139.0 69.5
-0.48 0.454 0.596
2
I59 200.0 135.0 67.5
-0.43 0.456 0.594
3
I69 200.0 53.0 26.5
0.60 0.379 0.510
4
I73 200.0 50.0 25.0
0.65 0.069 0.094
-------------------------------------------------------------------------
Calibration of the main
test items is computed as in the other examples. Without altering
the item parameter estimates of those items, parameter estimates
for the variants are computed with respect to the latent dimension
determined by the main items.
>CALIB CRIT=.005, CYCLES=10, NEWTON=2,
FLOAT, ACCEL=0.5;
(Output omitted)
SUBTEST
MAINTEST; ITEM PARAMETERS AFTER
CYCLE 6
ITEM INTERCEPT
SLOPE THRESHOLD LOADING ASYMPTOTE
CHISQ DF
S.E. S.E. S.E. S.E. S.E. (PROB)
-------------------------------------------------------------------------
I26| 0.451 | 0.356
| -1.267 |
0.336 | 0.000
| 3.2 7.0
|
0.648* | 0.087*
| 1.794* | 0.082*
| 0.000* | (0.8671)
| | | | | |
I27| 0.028 | 0.745
| -0.038 |
0.598 | 0.000
| 2.0 6.0
|
0.692* | 0.150*
| 0.928* | 0.120*
| 0.000* | (0.9187)
| | | | | |
(Similar output omitted)
I68| 0.963 | 0.561
| -1.716 |
0.490 | 0.000
| 4.7 6.0
|
0.922* | 0.138*
| 1.466* | 0.120*
| 0.000* | (0.5863)
| | | | | |
I72| -0.018 | 0.718
| 0.026 |
0.583 | 0.000
| 11.5 6.0
|
0.684* | 0.148*
| 0.952* | 0.120*
| 0.000* | (0.0731)
-------------------------------------------------------------------------
* STANDARD ERROR
LARGEST
CHANGE = 0.002542 82.8 129.0
(0.9995)
-------------------------------------------------------------------------
PARAMETER MEAN STN DEV
-----------------------------------
SLOPE 0.609 0.218
LOG(SLOPE) -0.558 0.368
THRESHOLD 0.145
1.269
******************************
CALIBRATION
OF VARIANT ITEMS
VARIANT
******************************
-2
LOG LIKELIHOOD = 4545.534
SUBTEST
VARIANT ; ITEM PARAMETERS
AFTER CYCLE 6
ITEM INTERCEPT
SLOPE THRESHOLD LOADING ASYMPTOTE
CHISQ DF
S.E. S.E. S.E. S.E. S.E. (PROB)
-------------------------------------------------------------------------
I53| 0.585 | 0.607 | -0.963
| 0.519 |
0.000 | 0.0
0.0
|
0.104* | 0.109*
| 0.204* | 0.093*
| 0.000* | (1.0000)
| | | | | |
I59| 0.516 | 0.597
| -0.865 |
0.513 | 0.000
| 0.0 0.0
|
0.101* | 0.107*
| 0.197* | 0.092*
| 0.000* | (1.0000)
| | | | | |
I69| -0.696 | 0.580
| 1.200 |
0.501 | 0.000
| 0.0 0.0
|
0.000* | 0.000*
| 0.000* | 0.000*
| 0.000* | (1.0000)
| | | | | |
I73| -0.649 | 0.093
| 6.975 |
0.093 | 0.000
| 0.0 0.0
|
0.000* | 0.000*
| 0.000* | 0.000*
| 0.000* | (1.0000)
-------------------------------------------------------------------------
 |
In Phase 3, scores for
all 660 examinees are computed from the main test item response
and saved to an external file. Printing of the scores is suppressed,
except for the first three cases. The latent distribution
estimated from all 660 cases is computed and printed. Scores
are based on the unrescaled Phase 2 parameters, which are
then saved to an external file.
>SCORE METHOD=2,NOPRINT;
SCORES
WILL NOT BE COMPUTED FOR VARIANT ITEM SUBTESTS
PARAMETERS FOR SCORING,
RESCALING, AND TEST AND ITEM INFORMATION
METHOD
OF SCORING SUBJECTS:
EXPECTATION A POSTERIORI
(EAP; BAYES ESTIMATION)
TYPE OF PRIOR: NORMAL
SCORES WRITTEN TO FILE EXAMPL06.SCO
TYPE OF RESCALING: NONE REQUESTED
ITEM AND TEST INFORMATION: NONE REQUESTED
DOMAIN SCORE ESTIMATION: NONE REQUESTED
QUAD
TEST NAME POINTS
-----------------------
1
MAINTEST 10
-----------------------
GROUP
SUBJECT IDENTIFICATION
MARGINAL
WEIGHT TEST TRIED RIGHT
PERCENT ABILITY S.E.
PROB
-------------------------------------------------------------------------
1
01021119001
|
|
1.00
MAINTEST 20 8 40.00
| -0.4077 0.3699 | 0.000000
1
01041122001
|
|
1.00
MAINTEST 20 8 40.00
| -0.4104 0.3695 | 0.000000
1
01051219001
|
|
1.00
MAINTEST 20 3 15.00
| -1.2375 0.4662 | 0.000000
-------------------------------------------------------------------------
SUMMARY
STATISTICS FOR SCORE ESTIMATES
======================================
CORRELATIONS
AMONG TEST SCORES
MAINTEST
MAINTEST 1.0000
MEANS,
STANDARD DEVIATIONS, AND VARIANCES OF SCORE ESTIMATES
TEST: MAINTEST
MEAN: 0.0919
S.D.: 0.8984
VARIANCE: 0.8071
ROOT-MEAN-SQUARE
POSTERIOR STANDARD DEVIATIONS
TEST: MAINTEST
RMS: 0.4526
VARIANCE: 0.2048
EMPIRICAL
RELIABILITY: 0.7976
MARGINAL
LATENT DISTRIBUTION(S)
===============================
MARGINAL
LATENT DISTRIBUTION FOR TEST MAINTEST
MEAN
= 0.092
S.D. = 0.979
1 2 3 4 5
POINT
-0.4000E+01 -0.3111E+01 -0.2222E+01 -0.1333E+01 -0.4444E+00
WEIGHT
0.1235E-03 0.2576E-02 0.2490E-01 0.1234E+00
0.3154E+00
6 7 8 9 10
POINT
0.4444E+00
0.1333E+01 0.2222E+01 0.3111E+01 0.4000E+01
WEIGHT
0.3313E+00 0.1585E+00 0.3875E-01 0.4743E-02
0.2767E-03
