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Table 29. Empirical ICCs and option frequencies |
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This Table display both the model expected score ogive, the predicted Item Characteristic Curve (ICC), and also the empirical observed average score per measure, the empirical ICC. See also Graphs Menu.
It also shows the relative frequency of each item response code for each measure level.
EMPIRICAL & MODEL ICCs- See also Graphs menu: Expected and Empirical ICCs
EMPIRICAL & MODEL ICCs : 1. What is the capital of Burundi?
++---------+---------+---------+---------+---------+---------++
O 1.0 + xxxxxxx *...*...*......+
B | ...... |
S | xx .. |
E | x .* |
R .8 + x x.. +
V | . |
E | x.. |
D | . x |
.6 + * +
A | x* |
V .5 + . +
E | . |
R .4 + x . +
A | x x . x |
G | x.xx |
E | . |
.2 + .. +
S | ..x |
C | ... |
O | ...... |
R .0 +.....*... x x +
E ++---------+---------+---------+---------+---------+---------++
-6 -4 -2 0 2 4 6
PERSON MEASURE
The model ICC is shown by '.'. this is the expected average score on the item for persons at each measure relative to the item.
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.
EMPIRICAL CODE FREQUENCIES - See also Graphs menu: Empirical category category curves
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.
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
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. "4" is the empirical frequency for category 4.
EMPIRICAL CODE FREQUENCIES: "4" : 1. A. FEEDING
++-------+-------+-------+-------+-------+-------+-------++
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 + 44 +
P 28 + .44 4 +
O 24 + ..4 .. 4 +
N 20 + 4 4 ..4 +
S 16 + .. 44 . +
E 12 + 4 . 4 4. +
% 8 + .4 4 44. +
4 + .... 444. +
0 +.... 44444444...................+
++-------+-------+-------+-------+-------+-------+-------++
-3 -2 -1 0 1 2 3 4
PERSON MEASURE