-------------------------------------------------------------------------------
       log:  /Applications/Stata/771bs2.smcl
  log type:  smcl
 opened on:  18 Jan 2004, 14:58:54



. set more off



. set seed 123456789



. local reps 1000



. 
. capture program drop muratio



. program define muratio, rclass
  1.         version 8.0
  2.         syntax varlist(min=2 max=2)
  3.         tempname ymu
  4.         summarize `1', meanonly
  5.         scalar `ymu' = r(mean)
  6.         summarize `2', meanonly
  7.         return scalar ratio = `ymu'/r(mean)
  8. end



. 
. webuse auto, clear
(1978 Automobile Data)



. tabstat price, by(foreign) stat(n mean semean)



Summary for variables: price
     by categories of: foreign (Car type)



 foreign |         N      mean  se(mean)
---------+------------------------------
Domestic |        52  6072.423  429.4911
 Foreign |        22  6384.682  558.9942
---------+------------------------------
   Total |        74  6165.257  342.8719
----------------------------------------



. g p_dom = price if foreign==0
(22 missing values generated)



. g p_for = price if foreign==1
(52 missing values generated)



. muratio p_dom p_for



. return list



scalars:
             r(ratio) =  .9510925132761489



. 
. bootstrap "muratio p_dom p_for" r(ratio), reps(`reps') saving(771bs2) replace



command:      muratio p_dom p_for
statistic:    _bs_1      = r(ratio)



Warning:  Since muratio is not an estimation command or does not set
          e(sample), bootstrap has no way to determine which observations are
          used in calculating the statistics and so assumes that all
          observations are used.  This means no observations will be excluded
          from the resampling due to missing values or other reasons.



          If the assumption is not true, press Break, save the data, and drop
          the observations that are to be excluded.  Be sure the dataset in
          memory contains only the relevant data.






Bootstrap statistics                              Number of obs    =        74
                                                  Replications     =      1000



------------------------------------------------------------------------------
Variable     |  Reps  Observed      Bias  Std. Err. [95% Conf. Interval]
-------------+----------------------------------------------------------------
       _bs_1 |  1000  .9510925  .0004643  .1081351   .7388945   1.163291   (N)
             |                                         .75699   1.179357   (P)
             |                                       .7785801    1.20562  (BC)
------------------------------------------------------------------------------
Note:  N   = normal
       P   = percentile
       BC  = bias-corrected



. 
. use 771bs2,clear
(bootstrap: muratio p_dom p_for)



. graph drop _all



. histogram _bs_1, normal name(g771bs2_r) xsize(9) ysize(7) ti("Bootstrap distr
> ibution of ratio of means")
(bin=29, start=.6723175, width=.02348913)



. graph export 771bs2.pdf, replace
(note: file 771bs2.pdf not found)



. log close
       log:  /Applications/Stata/771bs2.smcl
  log type:  smcl
 closed on:  18 Jan 2004, 14:59:03
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