Validity of Instrument Try- out Findings
Table 4.1. The Table of Students’ score in Validity Computation No. Code X
Y X
2
Y
2
XY
1 T-15 1
37 1
1369 37
2 T-21 1
37 1
1369 37
3 T-12 1
35 1
1225 35
4 T-19 1
35 1
1225 35
5 T-4 1
35 1
1225 35
6 T-26 1
35 1
1225 35
7 T-25 1
34 1
1156 34
8 T-23 1
31 1
961 31
9 T-22 1
28 1
784 28
10 T-2 1
28 1
784 28
11 T-16 0
28 784
12 T-7 1
28 1
784 28
13 T-17 1
26 1
676 26
14 T-18 0
26 676
15 T-9 0
26 676
16 T-3 0
25 625
17 T-20 1
25 1
625 25
18 T-10 1
23 1
529 23
19 T-11 0
22 484
20 T-28 1
20 1
400 20
21 T-6 0
20 400
22 T-8 0
19 361
23 T-14 1
16 1
256 16
24 T-13 1
16 1
256 16
25 T-5 0
15 225
26 T-24 0
12 144
27 T-1 1
13 1
169 13
28 T-27 0
12 144
Σ 18 707
18 19537
502
r
xy =
{ }
{ }
∑ ∑
∑ ∑
∑ ∑
∑
− −
− −
2 2
2 2
y y
N x
x N
y x
xy N
r
xy
=
} }
{ {
2 2
707 19537
28 18
18 28
707 18
502 28
− ×
− ×
−
r
xy
=
499849 547036
324 504
12726 14056
− −
−
r
xy
= 47187
180 1330
×
r
xy
= 8493660
1330
r
xy
= 388
, 2914
1330
r
xy
=0,456 From the computation above, the result of computing validity of the item
number 1 was 0,456. After that the writer consulted the result to the table of r product moment with the number of subjects N = 28 and significance level 5 it was 0,374.
Since the result of the computation was higher than r in the table, the index of validity of the item number 1 was considered to be valid. The list of the validity f each item
could be seen in appendix 3.