* Large dataset, so increase the memory
set memory 15m

* Open the dataset
use "c:/Elizabeth/Regression Course/Materials 2003/Data/project.dta"

* Create log file
log using "c:/Elizabeth/Regression Course/Materials 2003/project.txt", text replace

* Some tabulations of the data
tab mscd
tab eversmk
tab MALE
tab mscd eversmk
tab mscd MALE

* Generate some new variables to be used in the plotting
set seed 8843
gen junk1 = invnorm(uniform())/100
gen junk2 = invnorm(uniform())/10

gen mscd2 = mscd+junk1
gen LASTAGE2 = LASTAGE + junk2


* Question 1: Association between having a mscd and age
ksm mscd LASTAGE, generate(sm1)
graph mscd2 sm1 LASTAGE2, xlab ylab s(.o) b2("Age in Years") l1("Pr(mscd)") t1("MSCD VS. AGE")
gen lo1 = log(sm1 / (1-sm1))
graph lo1 LASTAGE2, xlab ylab s(.o) b2("Age in Years") l1("LogOdds(mscd)") t1("MSCD VS. AGE")


* Question 2: Effect modification of mscd/age association by gender
ksm mscd LASTAGE if MALE==0, generate(smf)
ksm mscd LASTAGE if MALE==1, generate(smm)
graph mscd2 smf smm LASTAGE2, xlab ylab s(.op) b2("Age in Years") l1("Pr(mscd)") t1("MSCD VS. AGE BY GENDER")
gen lof = log(smf / (1-smf))
gen lom = log(smm / (1-smm))
graph lof lom LASTAGE2, xlab ylab s(op) b2("Age in Years") l1("LogOdds(mscd)") t1("MSCD VS. AGE BY GENDER")


* Create some displays of the data
ksm mscd LASTAGE if MALE==0 & eversmk==0, generate(sm00)
ksm mscd LASTAGE if MALE==0 & eversmk==1, generate(sm01)
ksm mscd LASTAGE if MALE==1 & eversmk==0, generate(sm10)
ksm mscd LASTAGE if MALE==1 & eversmk==1, generate(sm11)


graph mscd2 sm00 sm01 LASTAGE2, s(.ox) xlab ylab b2("Age in Years") l1("Pr(mscd)") t1("MSCD VS. AGE For Females, Stratified by Smoking Status")
graph mscd2 sm10 sm11 LASTAGE2, s(.ox) xlab ylab b2("Age in Years") l1("Pr(mscd)") t1("MSCD VS. AGE For Males, Stratified by Smoking Status")

* Generate the log odds based on the kernel smooth
gen lo00 = log(sm00 / (1-sm00))
gen lo01 = log(sm01 / (1-sm01))
gen lo10 = log(sm10 / (1-sm10))
gen lo11 = log(sm11 / (1-sm11))

graph lo00 lo01 LASTAGE, s(ox) xlab ylab b2("Age in Years") l1("LogOdds(mscd)") t1("MSCD VS. AGE For Females, Stratified by Smoking Status")
graph lo10 lo11 LASTAGE, s(ox) xlab ylab b2("Age in Years") l1("LogOdds(mscd)") t1("MSCD VS. AGE For Males, Stratified by Smoking Status")

log close