In a short essay, define reliability, and list and discuss the three popular approaches for assessing reliability

What will be an ideal response?

Reliability refers to the extent to which a scale produces consistent results if repeated measurements are made on the characteristic. Reliability is determined by repeatedly measuring the construct or variable of interest. The higher the degree of association between the scores derived through this repeated measurement, the more reliable the scale. Popular approaches for assessing reliability are test-retest, alternative-forms, and internal consistency
methods.
a. In test-retest reliability, respondents are administered scales at two different times under as nearly equivalent condition as possible. The retest typically follows the original measurement by two to four weeks. The degree of similarity between the two measurements is determined by computing a correlation coefficient.
b. In order to test alternative-form reliability, two equivalent forms of the scale are constructed. The same respondents are measured at two different times using alternative scale forms. Correlation between the responses to the two equivalent forms of the scale provides a measure of reliability.
c. Internal consistency reliability is used to assess the reliability of a summated scale, or subscale, where scores for several items are summed to form a total score for a construct. In a scale of this type, each item measures some aspect of the construct measured by the entire scale. The items should be consistent in what they indicate about the characteristic.