C TTES 10
C ..................................................................TTES 20
C TTES 30
C SUBROUTINE TTEST TTES 40
C TTES 50
C PURPOSE TTES 60
C TO FIND CERTAIN T-STATISTICS ON THE MEANS OF POPULATIONS. TTES 70
C TTES 80
C USAGE TTES 90
C CALL TTEST (A,NA,B,NB,NOP,NDF,ANS) TTES 100
C TTES 110
C DESCRIPTION OF PARAMETERS TTES 120
C A - INPUT VECTOR OF LENGTH NA CONTAINING DATA. TTES 130
C NA - NUMBER OF OBSERVATIONS IN A. TTES 140
C B - INPUT VECTOR OF LENGTH NB CONTAINING DATA. TTES 150
C NB - NUMBER OF OBSERVATIONS IN B. TTES 160
C NOP - OPTIONS FOR VARIOUS HYPOTHESES.. TTES 170
C NOP=1--- THAT POPULATION MEAN OF B = GIVEN VALUE A. TTES 180
C (SET NA=1) TTES 190
C NOP=2--- THAT POPULATION MEAN OF B = POPULATION MEAN TTES 200
C OF A, GIVEN THAT THE VARIANCE OF B = THE TTES 210
C VARIANCE OF A. TTES 220
C NOP=3--- THAT POPULATION MEAN OF B = POPULATION MEAN TTES 230
C OF A, GIVEN THAT THE VARIANCE OF B IS NOT TTES 240
C EQUAL TO THE VARIANCE OF A. TTES 250
C NOP=4--- THAT POPULATION MEAN OF B = POPULATION MEAN TTES 260
C OF A, GIVEN NO INFORMATION ABOUT VARIANCES OFTTES 270
C A AND B. (SET NA=NB) TTES 280
C NDF - OUTPUT VARIABLE CONTAINING DEGREES OF FREEDOM ASSOCI- TTES 290
C ATED WITH T-STATISTIC CALCULATED. TTES 300
C ANS - T-STATISTIC FOR GIVEN HYPOTHESIS. TTES 310
C TTES 320
C REMARKS TTES 330
C NA AND NB MUST BE GREATER THAN 1, EXCEPT THAT NA=1 IN TTES 340
C OPTION 1. NA AND NB MUST BE THE SAME IN OPTION 4. TTES 350
C IF NOP IS OTHER THAN 1, 2, 3 OR 4, DEGREES OF FREEDOM AND TTES 360
C T-STATISTIC WILL NOT BE CALCULATED. NDF AND ANS WILL BE TTES 370
C SET TO ZERO. TTES 380
C TTES 390
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED TTES 400
C NONE TTES 410
C TTES 420
C METHOD TTES 430
C REFER TO OSTLE, BERNARD, 'STATISTICS IN RESEARCH', IOWA TTES 440
C STATE COLLEGE PRESS, 1954, CHAPTER 5. TTES 450
C TTES 460
C ..................................................................TTES 470
C TTES 480
SUBROUTINE TTEST (A,NA,B,NB,NOP,NDF,ANS) TTES 490
DIMENSION A(1),B(1) TTES 500
C TTES 510
C INITIALIZATION TTES 520
C TTES 530
NDF=0 TTES 540
ANS=0.0 TTES 550
C TTES 560
C CALCULATE THE MEAN OF A TTES 570
C TTES 580
AMEAN=0.0 TTES 590
DO 110 I=1,NA TTES 600
110 AMEAN=AMEAN+A(I) TTES 610
FNA=NA TTES 620
AMEAN=AMEAN/FNA TTES 630
C TTES 640
C CALCULATE THE MEAN OF B TTES 650
C TTES 660
115 BMEAN=0.0 TTES 670
DO 120 I=1,NB TTES 680
120 BMEAN=BMEAN+B(I) TTES 690
FNB=NB TTES 700
BMEAN=BMEAN/FNB TTES 710
C TTES 720
IF(NOP-4) 122, 180, 200 TTES 730
122 IF(NOP-1) 200, 135, 125 TTES 740
C TTES 750
C CALCULATE THE VARIANCE OF A TTES 760
C TTES 770
125 SA2=0.0 TTES 780
DO 130 I=1,NA TTES 790
130 SA2=SA2+(A(I)-AMEAN)**2 TTES 800
SA2=SA2/(FNA-1.0) TTES 810
C TTES 820
C CALCULATE THE VARIANCE OF B TTES 830
C TTES 840
135 SB2=0.0 TTES 850
DO 140 I=1,NB TTES 860
140 SB2=SB2+(B(I)-BMEAN)**2 TTES 870
SB2=SB2/(FNB-1.0) TTES 880
C TTES 890
GO TO (150,160,170), NOP TTES 900
C TTES 910
C OPTION 1 TTES 920
C TTES 930
150 ANS=((BMEAN-AMEAN)/SQRT(SB2))*SQRT(FNB) TTES 940
NDF=NB-1 TTES 950
GO TO 200 TTES 960
C TTES 970
C OPTION 2 TTES 980
C TTES 990
160 NDF=NA+NB-2 TTES1000
FNDF=NDF TTES1010
S=SQRT(((FNA-1.0)*SA2+(FNB-1.0)*SB2)/FNDF) TTES1020
ANS=((BMEAN-AMEAN)/S)*(1.0/SQRT(1.0/FNA+1.0/FNB)) TTES1030
GO TO 200 TTES1040
C TTES1050
C OPTION 3 TTES1060
C TTES1070
170 ANS=(BMEAN-AMEAN)/SQRT(SA2/FNA+SB2/FNB) TTES1080
A1=(SA2/FNA+SB2/FNB)**2 TTES1090
A2=(SA2/FNA)**2/(FNA+1.0)+(SB2/FNB)**2/(FNB+1.0) TTES1100
NDF=A1/A2-2.0+0.5 TTES1110
GO TO 200 TTES1120
C TTES1130
C OPTION 4 TTES1140
C TTES1150
180 SD=0.0 TTES1160
D=BMEAN-AMEAN TTES1170
DO 190 I=1,NB TTES1180
190 SD=SD+(B(I)-A(I)-D)**2 TTES1190
SD=SQRT(SD/(FNB-1.0)) TTES1200
ANS=(D/SD)*SQRT(FNB) TTES1210
NDF=NB-1 TTES1220
C TTES1230
200 RETURN TTES1240
END TTES1250