Census fluctuates widely from day to day and week to week--very rarely is it at the average. Over-reliance on the average daily census as a measure of hospital demand virtually assures hospitals that they will be staffed inappropriately most of the time. Despite the hospital industry's best efforts and intentions, high variability of inpatient census and the challenges of staffing a moving target make it virtually impossible for inpatient units to maintain the staffing plans and care ratios on which they are based. The impact of the flaw of averages on labor cost and patient flow is dramatic: The failure to control high inpatient variability can cost a larger hospital up to $8 million of excess cost or lost revenue. Some managers and execs may claim that their units or their hospital is "always full" and therefore that census variability is not a problem. This perception, however, doesn't square with the data.