A medical item that is used to care for a patient in a hospital is called a factor. For example, factors can be intravenous tubing, intravenous fluid, needles, shave kits, dressings, medications or even portable defibrillators.

The coronary care unit at a hospital in Florida investigated the relationship between the length in days of a coronary patient's hospital stay (variable name STAY), age of patient (AGE), number of factors (FACTOR), and whether or not this was a first coronary hospitalization for the patient (REPEAT = 0 for patients for whom the hospitalization was a first and REPEAT = 1 if they have been previously hospitalized for a coronary problem).

Data for 50 patients at the coronary care unit was gathered and a multiple regression model with STAY as the dependent variable and AGE, FACTORS, and REPEAT as the independent variables was estimated. The output for this model is shown in the tables on the next page.

Regression Statistics Multiple-R R Square Adj.RSqr StErr of Est Cases # missing 0.849 0.721 0.702 1.433 50 0 Summary Table Variable Coeff. Std.Err. Constant 7.087 -1.486 AGE 0.151 0.021 FACTOR 0.013 0.002 REPEAT 0.979 0.414 Analysis of Variance Source df Sum Sqrs mean Sqr F P-Value Regression 3 243.901 81.3 39.567 0.000 Residual 46 94.519 2.055 Total 49 338.42