* do-file for home assignment 3 of vhm 811, Fall semester 2007
* Henrik Stryhn

version 10
use "a3.dta", clear

* crude associations
cc case aircirc [fw=n]
tabulate case hsize [fw=n], chi2 expected
* odds-ratios against baseline category
cci 23 6 48 34
cci 20 6 29 34
cci 9 6 9 34
cci 58 6 13 34
* odds-ratios at a cutpoint
gen hsize200=hsize>=2
gen hsize300=hsize>=3
gen hsize400=hsize>=4
gen hsize500=hsize>=5
cc case hsize200 [fw=n]
cc case hsize300 [fw=n]
cc case hsize400 [fw=n]
cc case hsize500 [fw=n]

* Mantel-Haenszel estimate for aircirc
cc case aircirc [fw=n], by(hsize)
* association with outcome among exposure-negative
tabulate case hsize if aircirc==0 [fw=n], chi2 expected exact
cc case hsize200 if aircirc==0 [fw=n]
cc case hsize300 if aircirc==0 [fw=n]
cc case hsize400 if aircirc==0 [fw=n]
cc case hsize500 if aircirc==0 [fw=n]
* association with exposure among controls
tabulate aircirc hsize if case==0 [fw=n], chi2 expected

* frequency distribution of farm size among cases
tabulate case hsize [fw=n], row