(controlled by T2SELECT=, MRANGE=, CATREF=)

 

Multiple-choice items

Table 2.7 shows the measures that would be predicted to be observed for incorrect and correct responses if the persons responded exactly as the Rasch model predicts. "a" (an incorrect distractor) shows the average measure for persons in the sample who would be predicted to fail the item, and "d" (a correct distractor) shows the average measure for persons in the sample who would be predicted to succeed on the item. Compare this with Tables 2.5 and 2.6 for the empirical locations, and Table 2.2 for the sample-free locations.

 

TABLE 2.7 EXPECTED AVERAGE MEASURES FOR STUDENTS (scored) (ILLUSTRATED BY AN OBSERVED CATEGORY)

-4    -3     -2     -1      0      1      2      3      4

|------+------+------+------+------+------+------+------|  NUM   TOPIC

|                                  a                   d|   55  al07  newspaper

|                                         a             c   64  sa01  magazine

 

Table 2.17 is the same as Table 7, but the options are shown by their scored values, not by their codes in the data.

 

TABLE 2.17 EXPECTED AVERAGE MEASURES FOR STUDENTS (scored) (BY CATEGORY SCORE)

-4    -3     -2     -1      0      1      2      3      4

|------+------+------+------+------+------+------+------|  NUM   TOPIC

|                                  0                   1|   55  al07  newspaper

|                                         0             1   64  sa01  magazine

 

---

 

Polytomous items

Tables 2.7 & 2.17 plot the expected average person measures for each category score. It reflects how this sample were expected to use these categories. The plotted values cannot fall outside the range of the sample. Compare this with Tables 2.5 and 2.6 for the empirical locations, and Table 2.2 for the sample-free locations.

 

EXPECTED AVERAGE MEASURES BY CATEGORY FOR PUPILS

-2     -1       0       1       2       3       4       5

|-------+-------+-------+-------+-------+-------+-------|  NUM   ACT

|                  00      01            02             |    5  FIND BOTTLES AND CANS

|                                                       |

|                  00     01            02              |   23  WATCH A RAT

|                                                       |

|                 00     01           02                |   20  WATCH BUGS

|                 00     01          02                 |    4  WATCH GRASS CHANGE

|                 00     01          02                 |    8  LOOK IN SIDEWALK CRACKS

|-------+-------+-------+-------+-------+-------+-------|  NUM   ACT

-2     -1       0       1       2       3       4       5

 

   1 2  11 2 114346533233332222 322 2 1 1 1  1  1      11  PUPILS

    T        S         M         S         T