Table 29 Empirical ICCs and option frequencies

       EMPIRICAL & MODEL ICCs : 1. WATCH BIRDS

       -+-----+-----+-----+-----+-----+-----+-----+-----+-----+-

     2 +          x          xxxxxx xx x x..*...*.......*......+

       |                           .......                     |

O      |                        ...                            |

B      |                    x...                               |

S      |                 x  .                                  |

E      |              x   ..                                   |

R  1.5 +                x.                                     +

V      |               ..                                      |

E      |              .   xx                                   |

D      |             .                                         |

       |            .                                          |

A      |           .x                                          |

V    1 +    xx x x.  x x                                       +

E      |        ..                                             |

R      |       .                                               |

A      |      .    x                                           |

G      |     .                                                 |

E      |    .                                                  |

    .5 +  ..                                                   +

S      | .                                                     |

C      |.                                                      |

O      |                                                       |

R      |                                                       |

E      |                                                       |

     0 +  x   x                                                +

       -+-----+-----+-----+-----+-----+-----+-----+-----+-----+-

       -2    -1     0     1     2     3     4     5     6     7

                KID MEASURE

EMPIRICAL & MODEL ICCs

This Table displays, as dots, the model expected score ogive, also called the predicted Item Characteristic Curve (ICC) and the predicted Item Response Function (IRF). The model ICC is shown by '.'. this is the expected average score on the item for persons at each measure relative to the item.

The empirical observed average score per measure, the empirical ICC, is shown by x's.

Observed average scores on the items are shown by 'x'. When '.' and 'x' coincide, '*' is shown.

You can use this plot to compute the empirical item discrimination.

See also Graphs menu: Expected and Empirical ICCs

       EMPIRICAL CODE FREQUENCIES: "C"  : 2. 2

       ++------+------+------+------+------+------+------+------++

   100 +                                                         +

    96 +.......                                                  +

F   92 +       ....                                              +

R   88 +           ..                                            +

E   84 +             ..                                          +

Q   80 +               ..                                        +

U   76 +                 ..                                      +

E   72 +                   .                                     +

N   68 +                    .                                    +

C   64 +                     ..                                  +

Y   60 +                       .                                 +

    56 +                        .                                +

O   52 +                         .                               +

F   48 +                          .                              +

    44 +                           .                             +

R   40 +                            .                            +

E   36 +                             ..                          +

S   32 +                     C         .                         +

P   28 +               C C              .                        +

O   24 +                    C    C       ..                      +

N   20 +            C          C           ..                    +

S   16 +      C                   C CC  C    ..                  +

E   12 +                              C        ..                +

%    8 +                                  CC     ....            +

     4 +                                             ........    +

     0 +                                                     ....+

       ++------+------+------+------+------+------+------+------++

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

                              PERSON MEASURE

EMPIRICAL CODE FREQUENCIES: multiple-choice items

This shows the relative frequency of each item response code for each measure level.

For a multiple-choice item, with C as an incorrect distractor, this could like the plot below. The dots are the Rasch ogive for an incorrect answer.

- See also Graphs menu: Empirical category category curves

       EMPIRICAL CODE FREQUENCIES: "1" Neutral : 1. WATCH BIRDS

       -+-----+-----+-----+-----+-----+-----+-----+-----+-----+-

   100 +    NN N N   N N                                       +

    96 +                                                       +

F   92 +                                                       +

R   88 +                                                       +

E   84 +            N                                          +

Q   80 +                                                       +

U   76 +           N                                           +

E   72 +                                                       +

N   68 +                  NN                                   +

C   64 +                                                       +

Y   60 +                                                       +

    56 +          .                                            +

O   52 +       ... ...  N                                      +

F   48 +     ..       .                                        +

    44 +    .          ..                                      +

R   40 +  ..             .                                     +

E   36 + .            N   .                                    +

S   32 +.                N .                                   +

P   28 +                    .                                  +

O   24 +                    N..                                +

N   20 +                       .                               +

S   16 +                        ..                             +

E   12 +                          ..                           +

%    8 +                            ....                       +

     4 +                                .......                +

     0 +                                       ................+

       -+-----+-----+-----+-----+-----+-----+-----+-----+-----+-

       -2    -1     0     1     2     3     4     5     6     7

                KID MEASURE

EMPIRICAL CODE FREQUENCIES: polytomies

For a polytomous item, the percentage frequencies of responses, and the model ordinal probability, of each category are shown at each measure level. The dots are the model curve. "N" is the empirical frequency for category N = Neutral.