Data Analysis
Data analysis that examines the effect of nurse staffing on costs and LOS is complex. The majority of studies used multiple regression analysis. This helped control extraneous variables such as hospital size, location, and patient characteristics. Furthermore, the distribution of costs and LOS measures were reported as skewed. Therefore, some researchers transformed raw LOS and cost data to natural logarithmic values before completing multiple regression analysis. The growing complexity of data analysis methods in these studies was noted. Several studies collected data at patient and hospital levels and used multi-level regression to separately analyze the data at each level. Using multi-level regression, the investigators could control extraneous variables of patient characteristics and other contextual variables such as hospital size and location. More importantly, increasingly sophisticated ways of adjusting extraneous variables generated greater confidence in the interpretation of results.
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