Instrument Validity Test
What is validity. Validity is statement of data or information and how far its reach that collected on quetioner can measure what want to be measured. For example, researcher wants to measure employee job satisfaction, so all questions and statements on quetioner should be have relation with employee job satisfaction. None of statements or questions out from topic. Hence need do the instrument validity test.
Step by step validity test
- Define operationally a concept that will be measured. A concept that will be measured shall be formulated first so its operational can be done.
- Do instrument validity test to several responder. Responder is asked to answers available questions. Suggested minimum number of people who involve is 30 persons.
- Prepare tabulation of answer. Just ilustration, for example there are 10 questions which are filled by nine responder. The answers which is given by responder such as on following table.
- Calculates correlation between data on each statement with total score use product moment correlation technic formula as the follow:
r =
Name of Responder | Number of statement | Total | |||||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | ||
Ali Naufal Cici Daffa Luthfiah Sherene Dira Fizza Fauzan | 4 2 5 1 2 4 1 3 5 | 3 1 5 2 3 4 2 3 5 | 3 1 4 1 2 5 1 2 4 | 4 1 4 1 3 5 2 2 4 | 4 2 3 2 3 4 2 3 5 | 3 4 3 2 2 4 1 2 5 | 2 3 5 1 3 3 3 3 4 | 4 2 4 3 1 3 2 2 4 | 3 2 4 2 2 4 2 2 3 | 4 1 2 1 2 5 1 3 5 | 34 19 39 16 23 41 17 25 44 |
Remark: Contents of cell is ilustation of usage Likert scale of each statement from number 1 until number 10.
Where : 1= hardly disagree
2= disagree
3= could be ‘yes’ could be ‘not’
4= Agree
5= hardly agree
Using above formula, we could be calculated product moment correlation of statement number one as X, while total score as Y as the follow:
Responder | Variable | ||||
X | Y | X2 | Y2 | XY | |
Ali Naufal Cici Daffa Luthfiah Sherene Dira Fizza  Fauzann = 9 | 4 2 5 1 2 4 1 3 5 27 | 34 19 39 16 23 41 17 25 44 258 | 16 4 25 1 4 16 1 9 25 101 | 1156 361 1521 256 529 1681 289 625 1936 8354 | 136 38 195 16 46 164 17 75 220 907 |
Enters all that numbers into this formula:
r = 
So will be gained:
r = 
r = 
r = 
r = 
r = 
so : rY.X1 = 0,9608Examination to r need to be done to know which statement that should be considerated or to be reviewed.
If r > 0.5 , so the statement is reliable.
That’s all about instrument validity test. If you have question please send your email to: ifin.silbi@gmail.com or send it through comments.
Thank you.
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