/* Using transformed variables in  2 sample t-tests */

/* to transform variables, add lines to the DATA step that */
/*     define new variables as transformations of the old ones   */
/* For example, lrain is the log transformation of rainfall */
/*     and rrain is the reciprocal transformation of rainfall */

/* to do analyses on the transformed variables, just specify those */
/*   variable names in each proc step */

data rainfall;
  infile '~/WWW/stat401/data/case0301.txt';
  input rain code;
  
  lrain = log(rain);		/* N.B. this natural log */
  l10rain =  log10(rain);     /* this is log base 10 */
     
  srain = sqrt(rain);         /* Square root transformation */
  rrain = 1/rain;	          /* reciprocal transformation */
run;

/* sort the data, so that all observations from one treatment are together */
proc sort;
  by code;
       
proc boxplot;
  plot rain*code;
  plot lrain*code;
  
  run;

proc ttest data=rainfall;
  class code;
  var lrain rain;
  title 't-test for the cloud seeding data - natural scale and log scale';
run;