/* fig5_8b.do

  get bootstrap standard errors for binormal parameters a, b, and
      a / sqrt(1+b^2)

  see fig5_8.do for generation of curves

  Figure 5.8 (Example 5.6)

   programs required
       dfroc.ado  (v 1.3.0 or later)

   data required: dp2.dta
      Stover/Gorga DPOAE test data

  last update:  14 Aug 2003

*/
version 7
set more off
cap semt_profile
cap log close

pause on

use ${semt_data}dp2,clear

replace y = -y

log using ${semt_log}fig5_8b, replace

/*  choose f (stimulus frequency) = 1001; l (stimulus intensity) = 65  */

keep if f==1001 & l==65

/* get binormal parameters from fit with dfroc
   get b.s. se's separately via fig5_8b.do */

dfroc y d, nogr ns(5000) resfile(${semt_log}fig5_8b) ccsamp replace

dfroc y d, nogr ns(5000) resfile(${semt_log}fig5_8b2) replace
****************************************************************
/* get binormal parameters from -rocfit-

    will use cont(10) for now,

    estimates don't seem to be affected much by increasing number of categories
      with cont(#):

                              a     b
                 cont(5)   1.432  .806
                cont(10)   1.434  .818
                cont(20)   1.426  .806

*/

rocfit d y, cont(10)

/* estimate and var for   a/sqrt(1 + b^2)

                        = d_a/sqrt(2)

     where d_a = one of the indices returned by rocfit (see [R] rocfit, p.149)
*/

sca iauc = e(da)/sqrt(2)
sca se_iauc = e(se_da)/sqrt(2)

sca l iauc se_iauc

use ${semt_log}fig5_8b,clear
bstat
gen iauc = invnorm(auc)
sum iauc

use ${semt_log}fig5_8b2,clear
bstat
gen iauc = invnorm(auc)
sum iauc

log close