Where do promotion-readiness values come from?

A person's readiness for promotion is based on the time since the person's last promotion relative to the average time between promotions for people in the same job or position and grade.

For example, if the average time between promotions for people in the same job and grade is 5 years, a promotion appears due if the time since a person's last promotion is within range of 5 years. If the gap is outside this range, the promotion appears as either not due or overdue. Additional factors, such as performance and length of service, determine whether you decide to promote a person whose promotion appears due or overdue.