Even though some career colleges used pretests as an evaluation tool for faculty rather than an assessment tool for students knowledge, I certainly believe in the effectiveness of the pretest. They are a valuable tool in determining not only student knowledge, but in some instances they can give the instructor a hint of the learning abilities of the students.
Additionally, pretests can be a guiding light in determining and following course content. At the end of the course a posttest that shows improvement over the initial scores on the pretest sholud be a source of hapiness for the instructor, such a result means mission accomplished.