#problem 1
#a
library(alr4)
library(faraway)
data(ais)
fit=glm(Sex~RCC+WCC+Hc+Hg+Ferr+SSF+Bfat, data=ais, family=binomial)
summary(fit)
#b
#sex is purely binary data,
#so it is not appropriate to perform the lack of fit test
#c
predict(fit, newdata=data.f
#problem 1
#a
library(alr4)
data(MinnWater)
pairs(MinnWater)
#b
#allUse, muniUse and irrUse have especially high sample correlations with each
other
#c
mod=lm(muniUse~., data=MinnWater)
summary(mod)
#d
vif(mod)
which(vif(mod)>10)
#variables year, allUse,
#problem 1
#a
library(alr4)
library(MASS)
data(ais)
mod=lm(Wt~Ht, data=ais)
boxcox(mod)
#from the graph, lambda=0 is still in the 95% interval
#so the simplest transformation is to take lambda=0
#that is, log transformation
#b
mod1=lm(log(Wt)~Ht, data=ais
#question 1
#a
library(alr4)
data(lathe1)
mod=lm(Life~Feed+Speed+I(Feed^2)+I(Speed^2)+I(Feed*Speed), data=lathe1)
summary(mod)
#the interaction term is significant
#b
par(mfrow=c(2,2)
plot(mod)
#c
#from the Q-Q plot, we can say that the errors are not nor
BFHS <- read.table("~/Downloads/BFHS.dat", header=TRUE, quote="\")
#problem 1
#a
summary(BFHS)
#b
t.test(BFHS$Intervention-BFHS$ExternalComparison)
#the p value is 0.06067, which is larger than 0.05
#the difference between the two groups are not significa
STAT 425 Homework 1 Solution
Problem 1
Consider SLR model. Explain how 0 , 1 , p-value of 1 ,
and R2 will be affected.
In the following, we use symbols with hat to denote the original values of estimation, and use symbols with
tilde to denote the new va
STAT 425 Exam #1
October 5, 2016
7:00 8:30pm
Problem 1 : (2pt each) Circle the correct answer.
1. We can measure the proportion of the variation explained by the regression
model by:
(a) r
(b) R2
(c) 2
(d) F -stat
2. In a simple linear regression model Y