# Adjust the file path!
pop<-read.table("C:/Users/Helmut/Dropbox/population.tab")
# A table with the world population from 1950-2005:
pop
x<-pop[[1]]
x
y<-pop[[2]]
y
plot(x,y,xlab="Year",ylab="World Population (in billions)")
ylog<-log(y)
plot(x,ylog)
# Finding the least-squares fit:
lsf<-lsfit(x,ylog)
lsf
ylfit<-lsf$coefficients[[1]]+x*lsf$coefficients[[2]]
ylfit
# The next two commands graphs the log-plot and its best linear fit
plot(x,ylog)
abline(lsf)
# Now we will transform back to the original data:
yfit<-exp(ylfit)
yfit
plot(x,y,xlab="Year",ylab="World Population (in billions)")
lines(x,yfit)
# Now we will extend into the future:
xf<-c(x,2010,2015,2020,2025)
xf
yf<-c(y,NA,NA,NA,NA)
yf
ylfitf<-exp(lsf$coefficients[[1]]+xf*lsf$coefficients[[2]])
ylfitf
plot(xf,yf,xlab="Year",ylab="World Population (in billions)",ylim=c(2,10))
lines(xf,ylfitf)