RELIABILITY

 

Introduction:  The reliability of an instrument denotes the consistency of the measures obtained of an attribute, concept, or situation in a study or in clinical practice. Reliability is concerned with the precision, reproducibility, and comparability of a measurement method. An instrument with strong reliability demonstrates consistency in the participant scores obtained, resulting in less measurement error. For example, if you use a scale to measure blood pressures of 100 individuals at two points in time 2 weeks apart, you would expect the individuals' blood pressures to be relatively unchanged from one measurement to the next if the measurement procedures are reliable.

If two data collectors observe the same event and record their observations on a carefully designed data collection instrument, the measurement would be reliable if the recordings from the two data collectors were comparable. The equivalence of their results would indicate the reliability of the measurement technique. If responses vary each time a measure is performed, there is a chance that the instrument is unreliable, meaning that it yields data with a large random error.

Reliability also includes the validity or accuracy of measurement methods. An instrument is valid to the extent that it accurately measures what it was developed to measure. Thus, an instrument must be both reliable and valid to limit measurement error.

RELATED;

1.  Validity

2.  Writing a research proposal

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