The second aspect of reliability, stability, is said to occur when the same or similar scores are obtained with repeated testing with the same group of respondents. In other words, the scores are consistent from one time to the next. Stability is assessed through a test-retest procedure that involves administering the same measurement instrument to the same instrument to the same individuals under the same conditions after some period of time. Test-rest reliability is estimated with correlations between the scores at Time 1 and those at Time 2(to Time x). Two assumptions underlie the use of the test-retest procedure. The first required assumption is that the characteristic that is measured does not change over the time period. The second assumption is that the time period is long enough that the respondents’ memories of taking the test at time 1does not influence their scores at the second and subsequent test administrations