2. Parallel forms of the same test – In this procedure you construct two instruments that are intended to measure the same phenomenon. The two instruments are then administered to two similar populations. The results obtained from one test are compared with those obtained from the other. If they are similar, it is assumed that the instrument is reliable. The main advantage of this procedure is that it does not suffer from the problem of recall found in the test/retest procedure. Also, a time lapse between the two tests is not required. A disadvantage is that you need to construct two instruments instead of one. Moreover, it is extremely difficult to construct two instruments that are comparable in their measurement of a phenomenon. It is equally difficult to achieve comparability in the two population groups and in the two conditions under which the tests are administered.