methods
Most measures employed in the social sciences are constructed based on a small set of items sampled from the large domain of possible items that attempts to measure the same CONSTRUCT. It would be difficult to assess whether the responses to specific items on a measure can be generalized to the population of items for a construct if there is a lack of consistent responses toward the items (or a subset of the items) on the measure. In other words, high internal consistency suggests a high degree of interrelatedness among the responses to the items. [Source: The SAGE Encyclopedia of Social Science Research Methods; Internal Reliability]
internal reliability
reliability (research methods)