What is the minimum reliability coefficient recommended for an instrument to be considered reliable?

A reliability coefficient represents the degree to which an instrument consistently measures what it is intended to measure. A minimum reliability coefficient of 0.70 is often recommended for an instrument to be considered reliable in research contexts. This threshold indicates that the measurement is sufficiently consistent and trustworthy for use in studies, allowing for credible data collection and analysis.

A coefficient of 0.70 suggests that 70% of the variance in scores can be attributed to the actual differences among the respondents, rather than to random error. This level of reliability is generally viewed as adequate for many research applications, including clinical and social sciences.

Higher coefficients, such as 0.90 or 1.00, indicate even greater reliability, but achieving such high reliability may not always be feasible or necessary depending on the instrument's purpose and the context of its use. A coefficient of 0.50 is generally considered too low for research purposes, as it indicates that a significant portion of the measurement could be due to error, thereby compromising the validity and applicability of the findings.