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************************************************;
*** James P Geaghan                          ***;
*** EXST 700x two-sample t-test Examples     ***;
*** Assignment 09                            ***;
**********************************************************************;
*** Examples are from your text book                               ***;
*** Freund, Rudolph J., William J. Wilson and Donna L. Mohr. 2010. ***;
*** Statistical Methods, Academic Press (ELSIVIER), N.Y            ***;
**********************************************************************;

title1 "Assignment 09 - Pollution example"; 
data Multi (keep=AreaA AreaB diff)
     Pollution (keep=Area index); 
   INFILE 'datatab_5_13b.csv' dlm=',' dsd missover firstobs=2;
	  input AreaA AreaB;
         diff = AreaA - AreaB; output multi; 
         Area = 'A'; Index = AreaA; Output Pollution;
         Area = 'B'; Index = AreaB; Output Pollution;
datalines; run;
;
run;

*proc print data=Multi; run;
*proc print data=Pollution; run;

PROC ttest data=multi sides=u; 
   title2 'Pollution example done as a paired t-test with Proc TTEST'; 
   TITLE3 'One-tailed hypothesis'; 
   VAR diff;
RUN;

PROC ttest data=Pollution sides=u; 
   title2 'Pollution example done as a tw0-sample t-test with Proc TTEST'; 
   TITLE3 'One-tailed hypothesis'; 
   CLASS area;
   VAR Index;
RUN;



title1 "Assignment 09 - Light bulb life expectany example"; 
data bulbs; 
   INFILE 'datatab_5_17.txt' missover firstobs=2;
	  input brand $ life;
datalines; run;
;
run;

PROC ttest data=bulbs; 
   CLASS brand;
   VAR life;
   title2 "The two-sample t-test"; 
   TITLE3 'Two-tailed hypothesis'; 
RUN;

proc sort data=bulbs; by brand; 
PROC UNIVARIATE data=bulbs normal plots CIBASIC; by brand;
   VAR life;
   ods exclude BasicMeasures ExtremeObs ExtremeValues Modes
               MissingValues Quantiles TestsForLocation; 
RUN;

PROC BOXPLOT data=bulbs; plot life*brand; run;

/*

data bulbs2; set bulbs; 
   if life gt 2500 then delete;
run;

PROC ttest data=bulbs2; 
   CLASS brand;
   VAR life;
   title2 "The two-sample t-test"; 
   TITLE3 'Two-tailed hypothesis'; 
RUN;

proc sort data=bulbs2; by brand; 
PROC UNIVARIATE data=bulbs2 normal plots CIBASIC; by brand;
   VAR life;
   ods exclude BasicMeasures ExtremeObs ExtremeValues Modes
               MissingValues Quantiles TestsForLocation; 
RUN;

PROC BOXPLOT data=bulbs2; plot life*brand; run;

*/