Exercise 6

 

 

  1. Two models have been proposed for predicting the average length of patient

stay in hospital (Y) . Model I utilizes as independent variables age (X1),

infection risk (X2), and available facilities and services (X3). Model II uses as

independent variables number of beds (X1), infection risk (X2), and available

facilities and services (X3). The results are in file SENIC .

The description of variables is in file SENICDESCR .

    1. For each of the two proposed models, fit the first-order linear regression

      2. model with three independent variables.

    2. Calculate R2 for each model. Is one model cleary preferable in terms of

      3. this measure?

    3. For each model, obtain the residuals and plot them against Yhat and

against each of the three independent variables. Also prepare a normal

probability plot for each of the two fitted models. Analyze your plots and

state your findings. Is one model clearly preferable in terms of aptness?

 

2. Refer to the SENIC problem (problem 1 Exercise 6)

i. For each geographic region, regress infection risk (Y) against the

independent variables age (X1), routine culturing ratio (X2), average daily

census (X3), and available facilities and services (X4). Use the first-order

regression model with four independent variables. State the estimated

regression functions.

    1. Are the estimated regression functions similar for the four regions?

      2. Discuss.

    2. Calculate MSE and R2 for each region. Are these measures similar for the

four regions? Discuss.