Kidney failure patients are commonly treated on dialysis machines that filter toxic substances from the blood. The appropriate “dose” for effective treatment depends, among other things, on the duration of treatment and weight gain between treatments as a result of fluid buildup. To study the effects of thse two factors on the number of days hospitalized (attributable to the disease during a year, a random sample of 10 patients per group who had undergone treatment at a large dialysis centre was obtained. Treatment duration (factor A) was categorized into two groups: short duration (average dialysis for the year under 4 hours) and long duration: average dialysis time for year greater than or equal to 4 hours). Average weight gain between treatments (factor B) during the year was categorized into 3 groups: slight, moderate, and substantial. The data on number of days hospitalized was recorded.