Homework 4
Assigned: 19 September 2003
Due: 26 September 2003
C:\Documents and Settings\John Bailer\My
Documents\baileraj\Classes\Fall 2003\sta402\hw\Homework-4.doc
1. Repeat the regression analysis of the Manatee – Boat registration data
a. Fit the model MANATEE = 00 +1 NBOATSi + i
b. Fit the model MANATEE = 01 +1 [NBOATSNBOATSi-min(NBOATS)] + ] + i
c. Fit the model MANATEE = 02 +1[NBOATSNBOATSi-average(NBOATS)] + ] + i
Prepare a table summarizing the estimated regression coefficients, standard errors, P-values for
these three models. Hint: use ODS output to manipulate the coefficient information.
2. Refer to the 4 group (packaging method)- log-bacterial growth
study. In this exercise, you will compare the one-way anova model to
regression with coding.
a. Fit the anova model and obtain the estimated effects (estimates of
, 1, 2, 3, 4) using SOLUTION option to the GLM model statement.
proc glm data=meat order=data;
title2 fitting the one-way anova model via GLM;
class condition;
model logcount = condition/solution;
means condition;
run;
b. Define 4 indicator variables, one for each of the conditions. For
example, let ICO2 = 1 if condition=”CO2” and ICO2=0 otherwise. Define
the other 3 indicator variables similarly.
c. Can you fit a regression model with all indicator variables included? If so, how?
d. Fit 4 different regression models with 3 of the 4 indicator variables. Which fit matches the
solution from part a? What does this tell you about the coding in the model fit from part 2a?
model logcount = IPlastic IVacuum IMixed;
model logcount = IPlastic IVacuum ICO2;
model logcount = IPlastic IMixed ICO2;
model logcount = IVacuum IMixed ICO2;
3. Fit a regression model with a linear and a quadratic term to the nitrofen data using the
square root of “total” as the response variable. As an aside, the square root transformation is a
normalizing transformation for Poisson data and is often performed prior to fitting models that
