52
H. Test Instruments
The research instruments used previously should be tested first. The goal of trials for these instruments was to determine the validity and
reliability of the instrument so it can be known whether or not the instruments used in research. Trials conducted instruments was the student
class of XI IPS SMA N 1 Ngaglik of 30 students as the respondents. The reason for conducting the trials conducted in SMA N 1 Ngaglik was to
know the level achievement by student class of XI IPS SMA N 2 Sleman since they almost had the same level one to another.
1. Validity Instrument
An instrument is valid if it is able to measure and disclose the data of the researched variable. To check the validity of this research is
using Product Moment Correlation.
n XY X Y
r
xy =
{n X
2
X
2
}{n Y
2
Y
2
}
Descriptions : r
xy
= the correalation coefficient between the variables X and Y
N = the number of respondents
∑X = the number of items
∑X
2
= the number of squares score items ∑Y
= total score items ∑Y
2
= total squares score items ∑XY
= total multiple X and Y Suharsimi Arikunto, 2010: 213
53 Value of r
value
will be consulted with r
table
at a significance level 5. If the value of r
value
is greater than or equal to 5 r
table
the item of the instrument in question is valid and if known the value r
value
is smaller than r
table
the instrument is not valid. To check the validity of instruments are using data processing
application programs. Based on the results of data analysis that Locus of Control consists of 30 item statements, Student Perceptions of
Teacher Teaching Methods consists of 30 items statement, and Parents Concern consist of 25 items statement. After having tested to 30
students of Class XI IPS SMA Negeri 1 Ngaglik, then proceeds the questionnaire of Locus of Control from 30 items, 3 items expressed
fall Invalid, Student Perceptions of Teacher Teaching Methods from 30 items, 11 items expressed fall Invalid and Parents Concern from
25 item 7 declared Invalid. Instruments of the validity of the test results are summarized in the table as follows:
54 Tabel 8. The Result of Validity Instruments
Variable Total of
items Total
Invalid number
items Invalid
item number
Total Valid
number items
Locus of Control X1 30
3 2,3,4
27 Student Perceptions of
Teacher Teaching
Methods X2 30
11 3,5,14
16,20,22 23,25,29
30 19
Parents Concern X3 25
7 11,12,13
14,18,20 24
18
Source. The primary data source has processed. The items fall or not valid have removed and the items are valid
according to researcher is still represented each indicator that wants disclosed, so that the instrument is still eligible to use.
2. Reliability Instrument
Kategori