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According to the criterions, the item number 1 was easy because ID = 0.87. In this analysis eight items were categorized difficult, there were 11, 21, 28,
35, 45, 47, 51, and 53. Twenty two items were categorized medium, there were 6, 7, 8, 9, 10, 13, 14, 15, 17, 20, 22, 25, 27, 33, 34, 37, 38, 41, 43, 46, 48, and 49.
Twenty six items were categorized easy, there were 1, 2, 3, 4, 5, 12, 16, 18, 19, 23, 24, 26, 29, 30, 31, 32, 36, 39, 40, 42, 44, 50, 52, 54, 55, and 56.
4.1.4 Reliability
In this research, the writer used Spearman – Brown formula to analyze the reliability of the try out. The formula is stated as follows:
Where,
r
11
= reliability of the test
r
xy
=
r
½½
index correlation of split even – odd number
In the find the r
12 12
, used split even - odd number, which the formula:
Where,
r
xy = correlation reliability of the test item N = the number of the students participating in the try out
X = scores obtained from the first administration of the test item Y = scores obtained from the second administration of the test item
ΣXY = the sum of product of paired X and Y
xy xy
11
r 1
r .
2 r
+ =
{ }
{ }
2 2
2 2
xy
r ΣΥ
− ΝΣΥ
ΣΧ −
ΝΣΧ ΣΥ
ΣΧ −
ΝΣΧΥ =
43
ΣX² = the sum of the squared of x scores ΣY² = the sum of the squared of y scores
Criteria: The item is valid if
r
xy r table 5 from the number of subjects 38 =
0,321
There was the analysis of the validity item number,
Table 4.3 The Analysis of the Validity Item
No. X Y
X
2
Y
2
XY 1 24 23 576 529 552
2 23 24 529 576 552 3 19 26 361 676 494
4 21 24 441 576 504 5 22 23 484 529 506
6 21 23 441 529 483 7 18 24 324 576 432
8 19 22 361 484 418 9 19 22 361 484 418
10 20 21 400 441 420 11 18 22 324 484 396
12 21 19 441 361 399 13 20 20 400 400 400
14 16 23 256 529 368 15 18 21 324 441 378
16 19 20 361 400 380 17 15 24 225 576 360
18 18 21 324 441 378 19 18 20 324 400 360
20 15 23 225 529 345 21 15 23 225 529 345
22 16 22 256 484 352 23 14 18 196 324 252
44
24 17 15 289 225 255 25 15 17 225 289 255
26 12 17 144 289 204 27 11 17 121 289 187
28 11 15 121 225 165 29 12 14 144 196 168
30 12 13 144 169 156 31 9 15 81 225 135
32 12 11 144 121 132 33 7 15 49 225 105
34 7
13 49 169 91 35 7
11 49 121 77 36 6
10 36 100 60 37 8
4 64 16 32 38 3
5 9 25 15 Σ
578 700 9828
13982 11529
By using that formula, we obtain that:
r
xy = .
38 x 11529 – 578 x 700 .
{38 x 9828 – 578 } { 38 x 13982 – 700}
r
xy = 0.8306 The result of
r
xy is applied to the reliability formula, r
11
= .
2 x 0.831 .
1 + 0.38 r
11
= 0.907 On
α = 5 with N= 38 it was obtained r
tabel
= 0.321, because of rxy 0.907 r table 0.321, so the instrument was reliable.
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4.2 Tests Analysis
