*Open the log file; the path and name of the files are specific to your computer;

log using "C:\Documents and Settings\student\Desktop\Lab1\lab1.log"
infile week1-week9 using "C:\Documents and Settings\student\Desktop\Lab1\pigs.raw"
browse
save "C:\Documents and Settings\student\Desktop\Lab1\pigs.dta"
clear all
use "C:\Documents and Settings\student\Desktop\Lab1\pigs.stata.dta", clear
edit
clear all
use "C:\Documents and Settings\student\Desktop\Lab1\pigs.dta"
edit
*Genearate the id=observation number
generate id=_n
move id week1
list
list 1/5
list in 1/5
describe 
save "C:\Documents and Settings\student\Desktop\Lab1\pigs.dta", replace
*reshape the dataset into long format;

reshape long week, i(id) j(visit)
sort id visit
list in 1/5
* Plot in fig3.1 in DHLZ
twoway line week visit, s(i)

*To obtain Fig3.2 in DHLZ:

reshape wide
*One way of generating the standardized weight  
summarize week1
gen sweek1=(week1-25.02)/2.47

* A simpler way:
egen sweek1=std(week1)
egen sweek2=std(week2)
egen sweek3=std(week3)
egen sweek4=std(week4)
egen sweek5=std(week5)
egen sweek6=std(week6)
egen sweek7=std(week7)
egen sweek8=std(week8)
egen sweek9=std(week9)

reshape long week sweek, i(id) j(visit)
sort id visit
twoway line sweek visit, s(i)

*Linear regression;
regress week visit

*Close the log file
log close

exit, clear