The document discusses best practices for staffing adult inpatient units based on patient census and acuity. It provides background on the history of patient classification systems and acuity tools. Several studies concluded that there is a need for a universal acuity tool and that staffing should consider multiple factors beyond just patient ratios, including acuity, skill mix, and nursing workload. While some tools have been developed and tested, more research is still needed to establish standardized acuity measurement and determine optimal staffing levels based on patient acuity.