ABSTRACT
The quasi experiment (QE) includes many different kinds of designs, usually used to evaluate the impact of an ongoing program (X) on one or more indicators of output or outcome (Y). QEs have two characteristics in common. First, they make before-and-after time-series (TS) comparisons. Second, and unique to the QE, the researcher selects the groups to be compared so that they are as similar as possible in all respects, except that one group has the program and the other group does not or has a different program. The Posttest-Only Comparison-Group (PTCG) is the first real QE. It compares post program outcome scores in a school with the Companion Computers in the Classroom (CCC) program to the outcome scores (Yt) for a similar school without the program. One of the most common ways to select a natural comparison group is to use those on the waiting list for a service as a comparison group.
