r22 =
23.
= (34+23+39+45+31+38+33+34+22+33+36+32+26+29+19+23+40+23+26+22) / 20 = 30,4
r23 =
24.
= (34+14+21+26+30+39+45+31+38+33+32+24+21+34+26+27+32+26+22+27+19+17+31+39+36+35+32+19+23+26+30+28) / 33 = 28,9
r24 =
25.
= (34+21+39+45+25+31+38+33+32+36+21+34+22+26+25+27+26+27+27+23+39+36+29+40+23+26+22+28) / 29 = 29,56
r25 =
26.
= (34+23+14+21+30+39+45+31+38+33+18+32+36+24+34+22+26+25+32+22+19+17+31+39+36+35=32+29+19+23+40+23+26+30+25) / 35 = 28,66
r26 =
27.
= (34+21+30+39+45+25+38+33+36+34+22+26+33+27+39+36+35+32+26+23+40+30) / 22 = 32
r27 =
28.
=(34+23+14+21+26+30=39+31+38+32+36+34+22+26+25+15+27+32+26+22+27+27+19+17+23+31+39+32+26+29+19+13+40+15+23+26+30+22+28+25) / 40 = 26,85
r28 =
29.
= (34+18+30+39+25+31+38+32+36+34+27+22+27+23+23+28) / 16 = 29,2r29 =
30.
= (34+23+21+26+30+39+45+38+33+18+32+36+24+34+22+33+27+32+26+22+27+17+31+39+36+35+26+23+40+15+26+30+22+25) / 34 = 29,03
r30 =
31.
= (34+14+21+26+30+39+45+38+33+21+34+22+26+33+23+39+36+35+26+29+23+40+30) / 23 = 30,3
r31 =
32.
= (34+23+26+30+39+45+25+31+38+33+32+36+24+34+26+25+27+32+26+22+27+27+19+31+39+36+35+26+29+40+15+23+30+28+25) / 35 = 28,57
r32 =
33.
= (34+23+14+18+21+26+45+25+31+38+33+18+32+24+21+26+25+15+33+27+32+26+27+19+17+23+31+39+36+35+32+26+19+23+40+28+25) / 37 = 27,22
r33 =
34.
= (30+45+38+33+36+26+25+33+27+19+31+39+35+29+19+23+23+30+22) / 19 = 29,7
r34 =
35.
= (34+21+30+39+45+31+38+33+34+33+39+36+32+40+26+30) / 16 = 33,8r35 =
36.
= (34+23+14+18+21+26+39+45+25+31+38+33+18+32+36+21+34+22+26+15+33+27+32+26+22+27+27+19+17+23+31+39+36+35+32+26+29+19+
23+40+15+26+30+22+28+25) / 46 = 27,4
r36 =
37.
= (23+26+30+39+45+31+38+33+18+36+24+34+25+33+27+32+26+27+23+31+39+36+35+32+29+40+26+30+22+25) / 31 = 30,4
r37 =
38.
= (18+21+26+45+38+18+36+24+21+34+25+15+33+27+32+26+22+27+27+39+36+35+32+19+40+30+28) / 27 = 28,7
r38 =
39.
= (23+21+26+39+45+31+33+36+32+22+19+31+19+23+40+23+26+30) / 18 = 28,8
r39 =
40.
= (18+39+45+25+31+33+32+36+24+34+22+25+15+33+27+22+27+27+23+39+36+35+32+26+29+19=40+23+25) / 29 = 29
r40 =
41.
= (34+39+45+33+32+36+36+35+32+29+19+23+40+30) / 14 = 33r41 =
42.
= (34+23+30+45+38+33+18+36+34+33+26+31+39+26+29+40) / 16 = 32,2r42 =
43.
= (23+14+18+26+30+45+25+18+32+36+24+21+34+26+25+15+33+32+26+27+27+19+17+23+31+39+35+26+29+19+23+40+15+23+26+30+22+28+
25) / 39 = 26,3
r43 =
44.
= (34+23+18+30+39+45+25+31+38+33+18+32+36+24+21+25+27+32+27+17+23+31+39+36+35+32+26+23+40+15+26+30+22+28+25) / 35 = 28,74
r44 =
45.
= (34+23+14+26+30+39+45+31+38+33+32+36+24+21+34+22+26+33+27+32+26+22+27+31+39+36+35+32+26+23+40+23+22+28+25) / 35 = 29,6
r45 =
46.
= (18+39+45+38+33+21+33+27+19+23+26+25) / 12 = 28,92r46 =
47.
= (14+26+30+25+38+32+36+24+25+15+27+17+39+29+19+23+22) / 17 = 25,9r47 =
48.
= (34+18+26+30+39+45+25+31+38+33+18+32+36+21+34+22+26+15+33+27+32+26+22+27+27+19+17+23+31+39+36+35+32+26+29+23+40+15+
26+30+28+25) / 42 = 28,36
r48 =
49.
= (30+39+45+31+38+33+32+36+21+34+25+15+33+27+32+22+27+19+31+36+35+32+29+40+23+22+25) / 28 = 30
r49 =
50.
= (45+36+35) / 3 = 38,7r50 =
Коэффициент дискриминации может принимать значения от -1 до +1. Задания с отрицательным коэффициентом дискриминации оцениваются как непригодные, в нашем случае это задания № 05, 28, 33, 43, 47.
2.3. Вычисляем индекс дискриминативности (разность между долей лиц, отвечающих в соответствии с ключом, из лучшей и худшей групп) по формуле:
где D - индекс дискриминативности,
, - число испытуемых, выполнивших данное задание в высокой и низкой контрастных группах, , - объемы контрастных групп.Для вычисления объема контрастных групп отсекается по 27% испытуемых из группы с высокими и низкими показателями от общего числа испытуемых.
= 29 - 29·0,27 = 29 – 7,83 = 21,17 = 21 - 21·0,27 = 21 – 5,67 = 15,33D1 = 19/21,17 – 9/15,33 = 0,9 – 0,6 = 0,3
D2 = 17/21,17 – 4/15,33 = 0,8 – 0,26 = 0,54
D3 = 24/21,17 – 10/15,33 = 1,13 – 0,65 = 0,48
D4 = 22/21,17 – 11/15,33 = 1,04 – 0,72 = 0,32
D5 = 25/21,17 – 18/15,33 = 1,18 – 1,17 = 0,01
D6 = 17/21,17 – 2/15,33 = 0,8 – 0,13 = 0,67
D7 = 24/21,17 – 12/15,33 = 1,13 – 0,78 = 0,35
D8 = 27/21,17 – 14/15,33 = 1,3 – 0,9 = 0,4
D9 = 2/21,17 – 1/15,33 = 0,09 – 0,06 = 0,03
D10 = 19/21,17 – 7/15,33 = 0,9 – 0,46 = 0,44
D11 = 21/21,17 – 5/15,33 = 0,99 – 0,33 = 0,66
D12 = 11/21,17 – 6/15,33 = 0,52 – 0,39 = 0,13
D13 = 20/21,17 – 10/15,33 = 0,94 - 0,65 = 0,29
D14 = 25/21,17 – 9/15,33 = 1,18 – 0,59 = 0,59
D15 = 28/21,17 – 15/15,33 = 1,32 – 0,98 = 0,34
D16 = 25/21,17 – 9/15,33 = 1,18 – 0,59 = 0,59
D17 =24/21,17 – 13/15,33 = 1,13 – 0,85 = 0,28
D18 = 13/21,17 – 5/15,33 = 0,61 – 0,33 = 0,28
D19 = 12/21,17 – 5/15,33 = 0,57 – 0,33 = 0,24
D20= 25/21,17 – 16/15,33 = 1,18 – 1,04 = 0,14
D21 = 15/21,17 – 8/15,33 = 0,7 – 0,5 = 0,2
D22 = 6/21,17 – 1/15,33 = 0,28 – 0,06 = 0,22
D23 = 14/21,17 – 6/15,33 = 0,66 – 0,39 = 0,27
D24= 24/21,17 – 9/15,33 = 1,13 – 0,6 = 0,53
D25 = 20/21,17 – 9/15,33 = 0,94 – 0,6 = 0,34
D26 = 21/21,17 – 14/15,33 = 0,99 – 0,9 = 0,09
D27= 18/21,17 – 4/15,33 = 0,85 – 0,26 = 0,59
D28= 24/21,17 – 16/15,33 = 1,13 – 1,04 = 0,09
D29= 11/21,17 – 5/15,33 = 0,52 – 0,33 = 0,19
D30= 23/21,17 – 11/15,33 = 1,09 – 0,72 = 0,37
D31= 17/21,17 – 6/15,33 = 0,8 – 0,39 = 0,41