1 REM *** HP TIME-SHARED BASIC PROGRAM LIBRARY ************************* 2 REM 3 REM T-TEST: 36170 (A401) REV A -- 9/71 4 REM TEST OF HYPOTHESES USING STUDENTS T DISTRIBUTION 5 REM 6 REM *** CONTRIBUTED PROGRAM **************************************** 9000 S1=S2=S3=T1=T2=T3=0 9001 DIM X(50),Y(50) 9002 READ Q,N1,N2 9003 MAT READ X(N1) 9004 MAT READ Y(N2) 9005 FOR I=1 TO N1 9006 T1=T1+X(I) 9007 S1=S1+X(I)^2 9008 NEXT I 9009 M1=T1/N1 9010 D1=SQR((S1-(^2/N1))/(N1-1)) 9011 IF N2=1 THEN 9051 9012 FOR I=1 TO N2 9013 T2=T2+Y(I) 9014 S2=S2+Y(I)^2 9015 NEXT I 9016 M2=T2/N2 9017 D2=SQR((S2-(T2^2/N2))/(N2-1)) 9018 IF Q >= 2.5 THEN 9025 9019 IF Q >= 1.5 THEN 9023 9020 D0=SQR(((N1-1)*(D1^2)+(N2-1)*(D2^2))/(N1+N2-2)) 9021 T0=(M1-M2)/(D0*SQR((1/N1)+(1/N2))) 9022 GOTO 9032 9023 T0=(M1-M2)/SQR((D1^2/N1)+(D2^2/N2)) 9024 GOTO 9032 9025 FOR I=1 TO N1 9026 T3=T3+X(I)-Y(I) 9027 S3=S3+(X(I)-Y(I))^2 9028 NEXT I 9029 M3=T3/N1 9030 DSQR((S3-(T3^2/N1))/(N1-1)) 9031 T0=(M3*SQR(N1))/D3 9032 PRINT "SAMPLE","SAMPLE SIZE","MEAN","STANDARD DEVIATION" 9033 PRINT 1,N1,M1,D1 9034 PRINT 2,N2,M2,D2 9035 IF Q >= 1.5 THEN 9040 9036 PRINT :PRINT " THE POOLED DEVIATION IS";D0;"AND THE STUDENTS T" 9037 PRINT "VALUE IS";T0;"AT";N1+N2-2;"DEGREES OF FREEDOM." 9038 N=N1+N2-2 9039 GOTO 9056 9040 IF Q >= 2.5 THEN 9046 9041 F=((D1^2/N1+D2^2/N2)^2) 9042 F=F/((((D1^2/N1)^2)/(N1+1))+(((D2^2/N2)^2)/(N2+1)))-2 9043 PRINT :PRINT " THE UDENTS T VALUE IS";T0;"AT";F;"DEGREES OF FREEDOM." 9044 N=F 9045 GOTO 9056 9046 PRINT :PRINT " THE MEAN DIFFERENCE BETWEEN SETS OF OBSERVATIONS IS"; 9047 PRINT M3;",THE STANDARD DEVIATION OF THIS DIFFERENCE IS";D3 9048 PRINT "THE STUDENTS T TEST VALUE IS";T0;"AT";N1-1;"D.F." 9049 N=N1-1 9050 GOTO 9056 9051 T0=(M1-Y(1))/(D1*(SQR(1/N1))) 9052 PRINT :PRINT "THE SAMPLE MEAN IS";M1;",THE STANDARD DEVIATION IS";D1 9053 PRINT "AND THE T TEST VALUE IS";T0;"WITH";N1-1;"DEGREES" 9054 PRINT " FREEDOM WHEN COMPARED WITH A STANDARD OF";Y(1) 9055 N=N1-1 9056 G=T0^2 9057 M=1 9058 A=2*INT(M/2)-M+2 9059 B=2*INT(N/2)-N+2 9060 W=G*M/N 9061 Z=1/(1+W) 9062 IF B<>1 THEN 9068 9063 P=SQR(W) 9064 C=.31831 9065 D=C*Z/P 9066 P=2*C*ATN(P) 9067 GOTO 9070 9068 P=SQR(W*Z) 9069 D=.5*P*Z/W 9070 C=2*W/Z 9071 FOR J=B+2 TO N STEP 2 9072 D=(1+A/(J-2))*D*Z 9073 P=P+D*C/(J-1) 9074 NEXT J 9075 C=W*Z 9076 Z=2/Z 9077 B=N-2 9078 IF P>1 THEN P=1 ELSE IF P<=0 OR P=1 THEN P=0 99 P=1-P 9080 IF P=1 AND T0>1 THEN 9082 9081 IF P>.001 THEN 9083 9082 P=0 9083 P=P/2 9084 PRINT :PRINT "PROBABILITY OF T>= TO";T0;"WITH";N;"DEGREES OF FREEDOM" 9085 PRINT "IS";P 9900 DATA 1,12,12 9901 DATA 31,34,29,26,32,35,38,34,30,29,32,31 9902 DATA 26,24,28,29,30,29,32,26,31,29,32,28 9999 END