Further research on the impact of nurse staffing should address the following.
1. The evidence evaluated here suggests that costs and LOS are influenced by RN staffing levels. The few inconsistent findings may be explained by the various nurse staffing variables, cost measures, and LOS measures. Further research would be enhanced by standardizing measures of cost and LOS. Rather than measuring length of stay by using days of admission, LOS should be determined by using reliable methods such as number of days at midnight census or total hours. Using hospital expenditures as cost measures is a poor method to reflect variation of resource consumption among patients. Calculating costs using the micro-costing method is more reliable than using total hospital expenditures.