/*
	To obtain confidence intervals for probit

		z = alpha + beta*x

	we use 	

		_b[x] +/- invt(13,.95)*_se[x]		(assuming _N=15)

	when we should use

		_b[x] +/- invnorm(.975)*_se[x]

	which is better?
*/



mac def ALPHA=.2
mac def BETA=.4
mac def MODEL "logit y x"

capture program drop mkmodel /* n alpha beta */
program define mkmodel
	local n `1'
	drop _all
	set obs `n'
	gen x = _n/`n' 
	gen z = $ALPHA + $BETA*x
	gen p = exp(z)/(1+exp(z))
	gen y = p>=uniform()
end

capture program drop gens
program define gens
	gen alpha=.
	gen salpha=.
	gen beta=.
	gen sbeta=.
end

capture program drop sto
program define sto
	replace alpha = _b[_cons] in `1'
	replace salpha = _se[_cons] in `1'
	replace beta = _b[x] in `1'
	replace sbeta = _se[x] in `1'
end

capture program drop reports
program define reports
	report 95 `1'-2 $ALPHA alpha salpha 
	report 95 `1'-2 $BETA  beta  sbeta
end