The last five chapters have given a detailed view of each of the key elements of the assessment center method. We now step back from our detailed analysis of the elements to take a broader look at the effectiveness of the method as a whole: We analyze the extent to which the assessment center has validity. Validity is a general concept covering evidence that an assessment or development procedure is capable of achieving its stated purposes. Because any assessment technique can be used for a variety of purposes, many different types of evidence must be considered. For our purposes here, we consider whether the accumulated evidence supports the three main applications of the assessment center method covered in this book: prediction for selection/ promotion, diagnosis, and development. As we do this, our evaluation of validity covers all the steps taken to develop and implement an assessment center, because the results of all these steps provide relevant evidence. Specifically, we see that in the better assessment centers:

Dimensions are chosen on the basis of careful job analysis or competency modeling. Different dimensions are chosen for different purposes, and different definitions for dimensions are written for different levels of jobs, different organizations, and different cultures.