Interviews, survey forms, questionnaires, and timekeeping systems are examples of tools
that can be used to collect data on resource drivers. Notice that tracking the effort spent
on different activities is similar to tracking the time that laborers spend on different
jobs. However, there is one critical difference. The percent of effort spent on various
activities is usually fairly constant and may only need to be measured periodically (perhaps
annually). The same constancy property also exists for other types of resource drivers.
In effect, the labor time is a standard used to assign the cost of resources. Actual
times need not be constantly measured and used to achieve the desired cost assignment