---------------------------------------------------------------------------------------------------
       log:  C:\mydocs\MPH\Text\SecondEdition\WebDoFiles\1.4.14.Sepsis.log
  log type:  text
 opened on:  26 Dec 2007, 20:26:42

. *  1.4.14.Sepsis.log
. *
. *  Perform an independent t test comparing change in temperature
. *  from baseline after two hours in the ibuprofen group compared
. *  with that in the control group.
. *
. use C:\WDDtext\1.4.11.Sepsis.dta

. generate tempdif = temp0 - temp1
(35 missing values generated)

. *
. * Assume equal standard deviations in the two groups
. *
. ttest tempdif, by(treat)

Two-sample t test with equal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 Placebo |     212    .3119811    .0735218    1.070494    .1670496    .4569125
Ibuprofe |     208    .8845193    .0861504    1.242479    .7146746    1.054364
---------+--------------------------------------------------------------------
combined |     420    .5955238    .0581846    1.192429    .4811538    .7098938
---------+--------------------------------------------------------------------
    diff |           -.5725383    .1130981               -.7948502   -.3502263
------------------------------------------------------------------------------
    diff = mean(Placebo) - mean(Ibuprofe)                         t =  -5.0623
Ho: diff = 0                                     degrees of freedom =      418

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.0000         Pr(|T| > |t|) = 0.0000          Pr(T > t) = 1.0000

. *
. *  Assume unequal standard deviations in the two groups
. *
. ttest tempdif, by(treat) unequal

Two-sample t test with unequal variances
------------------------------------------------------------------------------
   Group |     Obs        Mean    Std. Err.   Std. Dev.   [95% Conf. Interval]
---------+--------------------------------------------------------------------
 Placebo |     212    .3119811    .0735218    1.070494    .1670496    .4569125
Ibuprofe |     208    .8845193    .0861504    1.242479    .7146746    1.054364
---------+--------------------------------------------------------------------
combined |     420    .5955238    .0581846    1.192429    .4811538    .7098938
---------+--------------------------------------------------------------------
    diff |           -.5725383    .1132579               -.7951823   -.3498942
------------------------------------------------------------------------------
    diff = mean(Placebo) - mean(Ibuprofe)                         t =  -5.0552
Ho: diff = 0                     Satterthwaite's degrees of freedom =  406.688

    Ha: diff < 0                 Ha: diff != 0                 Ha: diff > 0
 Pr(T < t) = 0.0000         Pr(|T| > |t|) = 0.0000          Pr(T > t) = 1.0000

. log close
       log:  C:\mydocs\MPH\Text\SecondEdition\WebDoFiles\1.4.14.Sepsis.log
  log type:  text
 closed on:  26 Dec 2007, 20:26:42
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