MENCARI KEBOLEHPERCAYAAN
INSTRUMEN YANG DIGUNAKAN

Sejauh manakah instrumen yang digunakan
boleh menghasilkan skor yang hampir sama
sekirannya ditadbir berulang kali

Perlu dilakukan pada peringkat ujian rintis
dan semasa kajian sebenar

Lazimnya menggunakan Kaedah Cronbach
Alpha (data skala) dan KR-20 (data dikotomi)
KEBOLEHPERCAYAAN
INSTRUMEN
Ketekalan Dalaman (Internal consistency)
•
Split-half Reliablity
•
Scorer/Rater Reliability
•
Kuder-Richardson 20 (KR-20)
•
Cronbach’s Alpha (α)
Data Dikotomi : KR-20
Data Skala : Cronbach α
KONSEP KEBOLEHPERCAYAAN
Researchers must demonstrate instruments are reliable since without reliability, research
results using the instrument are not replicable, and replicability is fundamental to the
scientific method. Reliability is the correlation of an item, scale, or instrument with a
hypothetical one which truly measures what it is supposed to. Since the true instrument
is not available, reliability is estimated in one of four ways:
•
Internal consistency: Estimation based on the correlation among the variables
comprising the set (typically, Cronbach's alpha, KR-20)
•
Split-half reliability: Estimation based on the correlation of two equivalent forms of
the scale (typically, the Spearman-Brown coefficient)
•
Test-retest reliability: Estimation based on the correlation between two (or more)
administrations of the same item, scale, or instrument for different times,
locations, or populations, when the two administrations do not differ on other
relevant variables (typically, the Spearman Brown coefficient)
•
Inter-rater reliability: Estimation based on the correlation of scores
between/among two or more raters who rate the same item, scale, or instrument
Nunnally and Bernstein (1994) provided guidance in the
interpretation of the reliability coefficient by stating that a value of
.70 is sufficient for early stages of research, but that basic research
should require test scores to have a reliability coefficient of .80 or
higher. When important decisions are to be made with test scores, a
reliability coefficient of .90 is the minimum with .95 or higher a
desirable standard. (Nunnally, J.C. & Bernstein, I.H. (1994). Psychometric Theory (3 Edition)).
rd
Nilai Koefisien
α
Interpretasi
Nilai Koefisien α
.90 and up
Interpretasi
Excellent
> 0.9
Excellent
> 0.8
Good
.80 - .89
Good
> 0.7
Acceptable
.70 - .79
Adequate
> 0.6
Questionable
> 0.5
Poor
< 0.5
Unacceptable
George, D., & Mallery, P. (2003). SPSS for Windows step by step:
A simple guide and reference. 11.0 update (4th ed.). Boston:
Allyn & Bacon.
below .70
May have limited
applicability
U.S. Department of Labor Employment and Training Administration
1999
Mencari Cronbach α
1
2
1
1
Kesan item kepada nilai koefisien
Cronbach α
**Pengguguran item bukan hanya
bergantung kepada nilai Cronbach
alfa
Melapor Kebolehpercayaan Instrumen
Secara keseluruhan instrumen kajian mempunyai nilai
kebolehpercayaan (Cronbach alfa) yang tinggi (α = 0.86). Ini
menunjukkan instrumen yang digunakan sesuai bagi menilai
penilaian guru terhadap buku teks. Menurut Nunally dan
Bernstein (1994), nilai .80 dan ke atas adalah mencukupi bagi
instrumen yang baru dibina atau pertama kali digunakan
manakal George & Mallery (2003) menyatakan nilai koefisiens
kebolehpercayaan α > 0.7 menunjukkan kebolehpercyaan
instrumen pada tahap baik.
Di samping itu, anda juga perlu melaporkan nilai kebolehpercayaan bagi setiap
aspek (sub-konstruk)