F. Instrument Test
Instrument test was conducted in SMK Muhammadiyah 2 Klaten Utara which was XI Accounting 1 as the trial class consisted of 30 students. In order to
collect valid data, instrument had to satified the requirements for validity and reliability.
a. Instrument Validity Test Before employing instrument to collect the data, test was firstly
conducted to see the validity of the instrument. Validity was measurement showed degree of validity of instrument Nana Syaodih, 2006: 228.
Formula used in the validity test was Karl Pearson’s product moment
correlation formula Suharsimi Arikunto, 2006: 72 which was
r
yx
=
∑ ∑ ∑ √{ ∑
∑ }{ ∑
∑ }
Information: r
yx
: correlation coefficient between X and Y variable ∑X
: sum of X score ∑Y
: sum of Y score ∑XY : sum of the product of X and Y score
N : number of subject
After value of r
hitung
was obtained, and it was consulted later with r
table
to find out the valid and invalid item. If r
hitung
was equal or more than r
table
with significant degree 5 then item of the instrument was valid. Conversely if
r
hitung
was less than r
table
then the instrument was invalid.
Instrument test was conducted in SMK Muhammadiyah 2 Klaten Utara on Wednesday, May 4 2016. From analysis result of 32 items instrument of
self-confidence, 26 items were valid while 6 items were invalid. From the analysis result of 27 items instrument of learning independence, 21 items
were valid while 6 items were invalid. The calculation result was further presented in the following table.
Table 4. Validation of Gratings for Instrument of Self-Confidence Number
Indicator Item Number
Valid Item Invalid Item
1 Communication
1,2,3,4,5 1,3,4,5
2 2
Firmness 6,7,8,9,10
6,7,9,10 8
3 Self-image
11,12 12
11 4
Patience 13,14,15
13,14,15 -
5 Self-respect
16,17,18,19 16,17,18,19
- 6
Self-awareness 20,21,22
20,22 21
7 Commitment
23,24,25 24,25
23 8
Positive Thinking 26,27,28,29,
30,31,32 27,28,29,30
31,32 26
Total 32
26 6
Table 5. Validation of Gratings for Learning Independence Number
Indicator Item Number
Valid Item Invalid Item
1 Dynamism
1,2,3,4 1,2,3,4
- 2
Self-confidence 5,6,7
6,7 5
3 Integrity
8,9,10,11,12 8,9,10,11,12
- 4
Autonomy 13,14,15,16,17
14,16,17 13,15
5 Responsibility
18,19,20,21,22 ,23
19,20,21,23 18,22
6 Initiative
24,25,26,27 24,25,27
26 Total
211 6
b. Reliability Test A good instrument must be valid and reliable. Instrument was
reliable if it gave the consistent result though it was employed by everyone and everytime.
To test the instrument’s reliability in this study, Alpha Coefficient formula was employed.
r
i
=
∑
Information: r
i
: instrument’s reliability k
: number of questions ∑
: sum of item’s varience : total variance
To interpret the reliability, the following indicators were used. Between 0.80 until 1.000 was very high
Between 0.60 until 0.799 was high Between 0.40 until 0.599 was moderate
Between 0.20 until 0.399 was low Referring to test criterion, if r
1
r
table
then the scale was reliable Sugiyono, 2009: 216. The reliability of the valid test items was then tested
by using Kuder-Richardson formula 20 K-R 20. The calculation result showed that the reliability value for instrument of self-confidence was 0.849.
It indicated that the instrument was highly-reliable. In addition to this, the reliability for instrument of learning independence was 0.667. It indicated
that the instrument was reliable. The result of the reliability and validity testing of both instruments was summarized as follow.
Table 6. The Summary of the Result of Validity and Reliability Testing for Instrument of Self-Confidence
Type of Instrument
Number of Initial
Item Number
of Invalid Item
Number of Valid
Item Reliability
Index Information
Trial 32 items
6 items 26 items
0.849 Very High
Table 7. The Summary of the Result of Validity and Reliability Testing for Instrument of Learning Independence
Type of Instrument
Number of Initial
Item Number
of Invalid Item
Number of Valid
Item Reliability
Index Information
Trial 27 items
6 items 21 items
0.067 High
G. Data Collection Technique
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