Validity and reliability of nursing workload measurement systems: review of validity and reliability theory.

Nursing workload measurement systems (WMSs) are used in inpatient and outpatient settings for staffing, scheduling, and budgeting. The nurse administrator can use WMS data to make wise decisions in these key areas providing the data are reliable and valid. Unfortunately, in most institutions, attention to issues of reliability and validity occurs only at system implementation and then the systems are left unattended. This article provides an overview of validity and reliability as it relates to WMSs. Part Two of this article will demonstrate how validity and reliability theory can be operationalized in an ongoing program for maintaining WMS reliability and validity.