version 9.2

log using C:\Teaching\IGP\log\17.chisquare.log, replace

* Chapter 16 & 17 
* modified on Feb. 13, 2007 by Leena Choi

***************************************************************************************
* Chapter 16
***************************************************************************************
use "C:\Teaching\IGP\data\ex1chapter16.dta", clear

* cohort study design
cs disease treatment, or woolf

* case-control design
cc disease treatment, woolf

* we can calculate RD, RR and OR without the data
csi 10 20 90 80, or woolf
csi 20 40 80 60, or woolf

***************************************************************************************
* Chapter 17
***************************************************************************************
* if you want to conduct chi square test using the previous example
tabulate disease treatment, chi

* calculate p-value corresponding to chi square statistic
di chi2tail(1, 3.92)

***** 3*2 table
use "C:\Teaching\IGP\data\ex2chapter17.dta", clear

* conduct chi square test for 3*2 table
tabulate disease treatment [weight=freq], chi

* confirm your calculation
di 8^2*(1/18 + 1/82) + 7^2*(1/27 + 1/123) + 14^2*(1/36+1/164)

* calculate p-value corresponding to chi square statistic
di chi2tail(2, 13.188799)

* display 2 tables of 2*2 table
use "C:\Teaching\IGP\data\EMS\perulung.dta", clear
gen fevcat = 0 
replace fevcat = 1 if fev1 > 1.58

table fevcat respsymptoms male 

log close