(controlled by MRANGE=, MAXPAGE=, T1I#=, T1P#=)

 

This table shows the distribution of the persons and items. The variable is laid out vertically with the most able persons, and most difficult items at the top. For rating (or partial credit) scales, each item is shown three times in Table 1.4. In the center item column, each item is placed at its mean calibration, i. e., this is the location of the center of the rating (or partial credit) scale - the location at which being ratings in the top and bottom category are equally probable. In the left-hand item column, the item is shown at the measure level (Rasch-Thurstone threshold) corresponding to a probability of .5 of exceeding (or being rated in) the bottom rating (or partial credit) scale category. In the right-hand item column, the item is shown at the measure level corresponding to a probability of .5 of being rated in (or falling below) the top rating (or partial credit) scale category. These locations are also shown in Table 2.3. Dichotomous items, "D", have only one location.

 

                           MAP OF PUPILS  AND ACTS                             

 MEASURE               |          P=50%|               |        P=50%  MEASURE 

  <more> ------PUPILS -+-ACTS    BOTTOM+-ACTS    CENTER+-ACTS    TOP -- <rare> 

    4.0              X +               +               +                  4.0  

                       |               |               |                       

                       |               |               |                       

                     X |               |               |                       

                       |               |               | X                     

                     X |               |               | X                     

    3.0                +               +               +                  3.0  

                     X |               |               | X                     

                     X |               |               | XX                    

                    XX |               |               |                       

                    XX |               | X             |                       

                    XX |               | X             |                       

    2.0            XXX +               +               + X                2.0  

                    XX |               | X             |                       

                    XX |               | XX            | X                     

                    XX |               |               | XX                    

                    XX | X             |               | XXX                   

                   XXX | X             |               | X                     

    1.0         XXXXXX +               + X             + X                1.0  

                   XXX | X             |               |                       

                 XXXXX | XX            | X             | XX                    

                   XXX |               | XX            | X                     

           XXXXXXXXXXX |               | XXX           | X                     

                  XXXX |               | X             | X                     

     .0        XXXXXXX + X             + X             + X                 .0  

                     X |               |               |                       

                       | X             | XX            | X                     

                     X | XX            | X             | X                     

                    XX | XXX           | X             |                       

                     X | X             | X             |                       

   -1.0              X + X             + X             + X               -1.0  

                       |               |               |                       

                    XX | XX            | X             |                       

                       | X             | X             | X                     

                     X | X             |               |                       

                       | X             |               |                       

   -2.0                + X             + X             + X               -2.0  

                       |               |               |                       

                       | X             |               |                       

                       | X             | X             |                       

                       |               |               |                       

                       |               |               |                       

   -3.0                + X             + X             +                 -3.0  

                       |               |               |                       

                       |               |               |                       

                       | X             |               |                       

                       |               |               |                       

                       |               |               |                       

   -4.0                + X             +               +                 -4.0  

  <less> ------PUPILS -+-ACTS    BOTTOM+-ACTS    CENTER+-ACTS    TOP -- <frequ>

 

In Table 1, each person or item is indicated by an "X", or, when there are too many "X"s to display on one line, several persons or items are represented by a "#". Less than that number by ".". So that if "#" represents 4, then "." represents 1 to 3.

 

The left-hand column locates the person ability measures along the variable. Observe that the top pupil (left column) is well above the top category of the most difficult act item (right-most column), but that all pupils are above the top category of the easiest item (bottom X in right-most column). "Above" here means with greater than 50% chance of exceeding.