Α.The Board will not publish the result until next week
B. No publication
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Answer:
Cronbach’s Alpha is a commonly employed index of test reliability.
Nunnally (1967) defined reliability as "the extent to which [measurements] are repeatable and that any random influence which tends to make measurements different from occasion to occasion is a source of measurement error" (p. 206). Source Cortina, J. M. (1993). What is coefficient alpha? An examination of theory and applications. Journal of applied psychology, 78(1), 98.
Alpha coefficient ranges in value from 0 to 1 and may be used to describe the reliability of factors extracted from dichotomous (that is, questions with two possible answers) and/or multi-point formatted questionnaires or scales (i.e., rating scale: 1 = poor, 5 = excellent).
The higher the score, the more reliable the generated scale is.
Nunnaly (1978) has indicated 0.7 to be an acceptable reliability coefficient but lower thresholds are sometimes used in the literature. Source Santos, J. R. A. (1999). Cronbach’s alpha: A tool for assessing the reliability of scales. Journal of extension, 37(2), 1-5.
Nunnally changed his reliability recommendations from his 1967 edition of Psychometric Theory in his 1978 edition. In 1967, he recommended that the minimally acceptable reliability for preliminary research should be in the range of .5 to .6, where as in 1978 he increased the recommended level to .7 (without explanation). Source Peterson, R. A. (1994). A meta-analysis of Cronbach's coefficient alpha. Journal of consumer research, 21(2), 381-391.
Table 1 Selected recommended reliability Levels on Page number 382 in Peterson, R. A. (1994). A meta-analysis of Cronbach's coefficient alpha. Journal of consumer research, 21(2), 381-391.
The coefficients alpha ranged from .06 to .99 with a mean of .77 and a median of .79. Peterson, R. A. (1994).
Reliability is concerned with the ability of an instrument to measure consistently.
For example, if a test has a reliability of 0.70, there is 0.51 error variance (random error) in the scores (0.70×0.70 = 0.49; 1.00 – 0.49 = 0.51). As the estimate of reliability increases, the fraction of a test score that is attributable to error will decrease. Source Tavakol, M., & Dennick, R. (2011). Making sense of Cronbach's alpha. International journal of medical education, 2, 53.