If a decision is made to form a composite based on several criterion measures, then the
question is whether all measures should be given the same weight or not (Bobko, Roth, & Buster,
2007). Consider the possible combination of two measures reflecting customer service, one
collected from external customers (i.e., those purchasing the products offered by the organization)
and the other from internal customers (i.e., individuals employed in other units within the
same organization). Giving these measures equal weights implies that the organization values
both external and internal customer service equally. However, the organization may make the
strategic decision to form the composite by giving 70 percent weight to external customer
service and 30 percent weight to internal customer service. This strategic decision is likely to
affect the validity coefficients between predictors and criteria. Specifically, Murphy and
Shiarella (1997) conducted a computer simulation and found that 34 percent of the variance in
the validity of a battery of selection tests was explained by the way in which measures of task
and contextual performance were combined to form a composite performance score. In short,
forming a composite requires a careful consideration of the relative importance of each criterion
measure.