## Loading required package: sm
## Package `sm', version 2.2-5: type help(sm) for summary information
## Loading required package: ltm
## Loading required package: MASS
## 
## Attaching package: 'MASS'
## The following object is masked from 'package:sm':
## 
##     muscle
## Loading required package: msm
## Loading required package: polycor
## Loading required package: mvtnorm
## Loading required package: sfsmisc

Estimation

##           est       sem  n
## [1,] 1.982657 0.7509139 20
## [2,] 1.628579 0.7441675 20
## [3,] 1.628579 0.7441675 20
## [4,] 1.628579 0.7441675 20
## [5,] 1.628579 0.7441675 20
## [6,] 1.628579 0.7441675 20

Item Parameters

Sort Item Parameters according to Item Discrimination

##     discrimination difficulty guessing
## A1           0.633     -4.265        0
## A2           0.633     -0.331        0
## A3           0.633     -2.891        0
## A4           0.633     -0.916        0
## A5           0.633     -3.705        0
## A6           0.633     -4.367        0
## A7           0.633     -2.985        0
## A8           0.633     -0.720        0
## A9           0.633     -2.236        0
## A10          0.633      1.332        0
## A11          0.633      4.411        0
## A12          0.633     -4.447        0
## A13          0.633     -3.987        0
## A14          0.633     -1.182        0
## A15          0.633     -1.759        0
## A16          0.633      2.929        0
## A17          0.633      1.139        0
## A18          0.633      4.669        0
## A19          0.633     -3.821        0
## A20          0.633     -3.201        0

Most difficult to easiest items

##     discrimination difficulty guessing
## A18          0.633      4.669        0
## A11          0.633      4.411        0
## A16          0.633      2.929        0
## A10          0.633      1.332        0
## A17          0.633      1.139        0
## A2           0.633     -0.331        0
## A8           0.633     -0.720        0
## A4           0.633     -0.916        0
## A14          0.633     -1.182        0
## A15          0.633     -1.759        0
## A9           0.633     -2.236        0
## A3           0.633     -2.891        0
## A7           0.633     -2.985        0
## A20          0.633     -3.201        0
## A5           0.633     -3.705        0
## A19          0.633     -3.821        0
## A13          0.633     -3.987        0
## A1           0.633     -4.265        0
## A6           0.633     -4.367        0
## A12          0.633     -4.447        0

Total item 1

There are several different patterns all with a score of 17
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 score theta
11 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
12 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
13 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 17 1.28
14 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 0 1 1 1 1 17 1.28
15 1 1 1 1 1 1 1 0 1 1 0 1 1 1 1 0 1 1 1 1 17 1.28
16 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 17 1.28
17 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
18 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 17 1.28
19 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 17 1.28
20 1 0 1 1 1 1 1 0 1 1 0 1 1 1 1 1 1 1 1 1 17 1.28
21 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
22 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
23 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
24 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 17 1.28
25 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 1 1 1 17 1.28
26 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 0 1 1 17 1.28
27 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 1 1 1 17 1.28
28 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 0 1 1 17 1.28
29 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 1 1 1 17 1.28
30 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 1 1 1 17 1.28
31 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
32 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 1 1 1 17 1.28
33 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 17 1.28
34 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
35 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
36 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
37 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 1 1 1 17 1.28
38 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 17 1.28
39 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28
40 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 0 1 0 1 1 17 1.28
41 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 1 17 1.28
42 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 17 1.28

Total item 18

There is a single scoring pattern (all answered only item 2 incorrectly) for a grade of 18
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 score theta
2 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
3 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
4 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
5 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
6 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
7 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
8 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
9 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629
10 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 1 1 1 18 1.629