HW4

library(TSA)

## 
## Attaching package: 'TSA'

## The following objects are masked from 'package:stats':
## 
##     acf, arima

## The following object is masked from 'package:utils':
## 
##     tar

data(winnebago)
plot(winnebago,type='o',ylab='Winnebago Monthly Sales')
abline(0,0,lwd=2,lty=1)

plot(log(winnebago),type='o',ylab='Log(Monthly Sales)')

percentage=na.omit((winnebago-zlag(winnebago))/zlag(winnebago))
plot(x=diff(log(winnebago))[-1],y=percentage[-1], ylab='Percentage Change',xlab='Difference of Logs')
abline(0,0,lwd=2,lty=1)

cor(diff(log(winnebago))[-1],percentage[-1])

## [1] 0.9646886