Original Program from program editor.
****************************************************;
*** Steele & Torrie (1980) Table 5.2 ***;
*** Percent digestability of corn silage was ***;
*** examined for sheep and steers. ***;
*** ***;
****************************************************;
options ps=61 ls=64 nocenter nodate nonumber;
TITLE1 'Two sample t-tests';
data silage; infile cards missover;
TITLE2 'Percent digestability of corn silage';
LABEL animal = 'Type of animal tested';
LABEL percent = 'Percent digestability';
input sheep steers;
animal = 'Sheep '; percent = sheep; output;
animal = 'Steers'; percent = steers; output;
cards; run;
57.8 64.2
56.2 58.7
61.9 63.1
54.4 62.5
53.6 59.8
56.4 59.2
53.2
;
proc print data=silage; var animal percent;
TITLE3 'Raw data listing';
run;
proc ttest data=silage; class animal; var percent;
TITLE3 'PROC TTEST results';
run;
*****************************************************;
*** Steele & Torrie (1980) Table 5.6 ***;
*** Percent fine gravel found in surface soils. ***;
*** Data from a study comparing characteristics ***;
*** of soil catagorized as "good" or "poor". ***;
*****************************************************;
options ps=61 ls=78 nocenter nodate nonumber;
TITLE1 'Two sample t-tests';
data dirt; infile cards missover;
TITLE2 'Percent fine gravel in surface soils';
LABEL soilqual = 'Soil quality evaluation';
LABEL percent = 'Percent fine gravel';
input good poor;
soilqual = 'good '; percent = good; output;
soilqual = 'poor'; percent = poor; output;
cards; run;
5.9 7.6
3.8 0.4
6.5 1.1
18.3 3.2
18.2 6.5
16.1 4.1
7.6 4.7
;
proc print data=dirt; var soilqual percent;
TITLE3 'Raw data listing';
run;
proc ttest data=dirt; class soilqual; var percent;
TITLE3 'PROC TTEST results';
run;
*******************************************************;
*** Steele & Torrie (1980) Exercise 5.5.6 ***;
*** The weights in grams of 10 male and 10 female ***;
*** juvenile ring-necked pheasants trapped in ***;
*** January in Wisconsin are given. Test the Ho ***;
*** that males were 350 grams heavier than females. ***;
*******************************************************;
options ps=61 ls=78 nocenter nodate nonumber;
TITLE1 'Two sample t-tests';
data birds; infile cards missover;
TITLE2 'Weight in gms of male & female pheasants';
LABEL sex = 'Sex of pheasant';
LABEL weight = 'Weight in grams';
input sex $ weight;
if sex eq 'Male' then AdjWT = Weight - 350;
else AdjWT = weight;
cards; run;
Female 1061
Female 1065
Female 1092
Female 1017
Female 1021
Female 1138
Female 1143
Female 1094
Female 1270
Female 1028
Male 1293
Male 1380
Male 1614
Male 1497
Male 1340
Male 1643
Male 1466
Male 1627
Male 1383
Male 1711
;
proc print data=birds; var sex weight adjwt;
TITLE3 'Raw data listing';
run;
proc ttest data=birds H0=-350; class sex; var weight;
TITLE3 'PROC TTEST results specifying a difference';
run;
proc ttest data=birds; class sex; var adjwt;
TITLE3 'PROC TTEST results on adjusted values';
run;
Below is output from the SAS log (bold) and output from the SAS Output window.
1 ****************************************************;
2 *** Steele & Torrie (1980) Table 5.2 ***;
3 *** Percent digestability of corn silage was ***;
4 *** examined for sheep and steers. ***;
5 *** ***;
6 ****************************************************;
7 options ps=61 ls=64 nocenter nodate nonumber;
8 TITLE1 'Two sample t-tests';
9
10
11 data silage; infile cards missover;
12 TITLE2 'Percent digestability of corn silage';
13 LABEL animal = 'Type of animal tested';
14 LABEL percent = 'Percent digestability';
15 input sheep steers;
16 animal = 'Sheep '; percent = sheep; output;
17 animal = 'Steers'; percent = steers; output;
18 cards;
NOTE: The data set WORK.SILAGE has 14 observations and 4
variables.
NOTE: DATA statement used (Total process time):
real time 0.03 seconds
cpu time 0.03 seconds
18 ! run;
26 ;
27 proc print data=silage; var animal percent;
28 TITLE3 'Raw data listing';
29 run;
NOTE: There were 14 observations read from the data set
WORK.SILAGE.
NOTE: The PROCEDURE PRINT printed page 1.
NOTE: PROCEDURE PRINT used (Total process time):
real time 0.01 seconds
cpu time 0.01 seconds
Two sample t-tests
Percent digestability of corn silage
Raw data listing
Obs animal percent
1 Sheep 57.8
2 Steers 64.2
3 Sheep 56.2
4 Steers 58.7
5 Sheep 61.9
6 Steers 63.1
7 Sheep 54.4
8 Steers 62.5
9 Sheep 53.6
10 Steers 59.8
11 Sheep 56.4
12 Steers 59.2
13 Sheep 53.2
14 Steers .
30 proc ttest data=silage; class animal; var percent;
31 TITLE3 'PROC TTEST results';
32 run;
NOTE: There were 14 observations read from the data set
WORK.SILAGE.
NOTE: The PROCEDURE TTEST printed page 2.
NOTE: PROCEDURE TTEST used (Total process time):
real time 0.00 seconds
cpu time 0.00 seconds
Two sample t-tests
Percent digestability of corn silage
PROC TTEST results
The TTEST Procedure
Statistics
Lower CL Upper CL
Variable animal N Mean Mean Mean
percent Sheep 7 53.437 56.214 58.991
percent Steers 6 58.834 61.25 63.666
percent Diff (1-2) -8.35 -5.036 -1.721
Statistics
Lower CL Upper CL
Variable animal Std Dev Std Dev Std Dev Std Err
percent Sheep 1.9348 3.0025 6.6116 1.1348
percent Steers 1.4369 2.302 5.6458 0.9398
percent Diff (1-2) 1.9174 2.7066 4.5955 1.5058
Statistics
Variable animal Minimum Maximum
percent Sheep 53.2 61.9
percent Steers 58.7 64.2
percent Diff (1-2)
T-Tests
Variable Method Variances DF t Value Pr > |t|
percent Pooled Equal 11 -3.34 0.0065
percent Satterthwaite Unequal 10.9 -3.42 0.0058
Equality of Variances
Variable Method Num DF Den DF F Value Pr > F
percent Folded F 6 5 1.70 0.5764
36 ***************************************************** ;
37 *** Steele & Torrie (1980) Table 5.6 *** ;
38 *** Percent fine gravel found in surface soils. *** ;
39 *** Data from a study comparing characteristics *** ;
40 *** of soil catagorized as "good" or "poor". *** ;
41 ***************************************************** ;
42 options ps=61 ls=78 nocenter nodate nonumber;
43 TITLE1 'Two sample t-tests';
44
45 data dirt; infile cards missover;
46 TITLE2 'Percent fine gravel in surface soils';
47 LABEL soilqual = 'Soil quality evaluation';
48 LABEL percent = 'Percent fine gravel';
49 input good poor;
50 soilqual = 'good '; percent = good; output;
51 soilqual = 'poor'; percent = poor; output;
52 cards;
NOTE: The data set WORK.DIRT has 14 observations and 4 variables.
NOTE: DATA statement used (Total process time):
real time 0.01 seconds
cpu time 0.00 seconds
52 ! run;
60 ;
61 proc print data=dirt; var soilqual percent;
62 TITLE3 'Raw data listing';
63 run;
NOTE: There were 14 observations read from the data set WORK.DIRT.
NOTE: The PROCEDURE PRINT printed page 3.
NOTE: PROCEDURE PRINT used (Total process time):
real time 0.01 seconds
cpu time 0.01 seconds
Two sample t-tests
Percent fine gravel in surface soils
Raw data listing
Obs soilqual percent
1 good 5.9
2 poor 7.6
3 good 3.8
4 poor 0.4
5 good 6.5
6 poor 1.1
7 good 18.3
8 poor 3.2
9 good 18.2
10 poor 6.5
11 good 16.1
12 poor 4.1
13 good 7.6
14 poor 4.7
64 proc ttest data=dirt; class soilqual; var percent;
65 TITLE3 'PROC TTEST results';
66 run;
NOTE: There were 14 observations read from the data set WORK.DIRT.
NOTE: The PROCEDURE TTEST printed page 4.
NOTE: PROCEDURE TTEST used (Total process time):
real time 0.00 seconds
cpu time 0.00 seconds
Two sample t-tests
Percent fine gravel in surface soils
PROC TTEST results
The TTEST Procedure
Statistics
Lower CL Upper CL Lower CL
Variable soilqual N Mean Mean Mean Std Dev Std Dev
percent good 7 5.0559 10.914 16.773 4.0819 6.3344
percent poor 7 1.5048 3.9429 6.3809 1.6987 2.6362
percent Diff (1-2) 1.3212 6.9714 12.622 3.4789 4.8515
Statistics
Upper CL
Variable soilqual Std Dev Std Err Minimum Maximum
percent good 13.949 2.3942 3.8 18.3
percent poor 5.8051 0.9964 0.4 7.6
percent Diff (1-2) 8.0086 2.5932
T-Tests
Variable Method Variances DF t Value Pr > |t|
percent Pooled Equal 12 2.69 0.0197
percent Satterthwaite Unequal 8.02 2.69 0.0275
Equality of Variances
Variable Method Num DF Den DF F Value Pr > F
percent Folded F 6 6 5.77 0.0509
71 *******************************************************;
72 *** Steele & Torrie (1980) Exercise 5.5.6 ***;
73 *** The weights in grams of 10 male and 10 female ***;
74 *** juvenile ring-necked pheasants trapped in ***;
75 *** January in Wisconsin are given. Test the Ho ***;
76 *** that males were 350 grams heavier than females. ***;
77 *******************************************************;
78 options ps=61 ls=78 nocenter nodate nonumber;
79 TITLE1 'Two sample t-tests';
80
81 data birds; infile cards missover;
82 TITLE2 'Weight in gms of male & female pheasants';
83 LABEL sex = 'Sex of pheasant';
84 LABEL weight = 'Weight in grams';
85 input sex $ weight;
86 if sex eq 'Male' then AdjWT = Weight - 350;
87 else AdjWT = weight;
88 cards;
NOTE: The data set WORK.BIRDS has 20 observations and 3 variables.
NOTE: DATA statement used (Total process time):
real time 0.01 seconds
cpu time 0.01 seconds
88 ! run;
109 ;
110 proc print data=birds; var sex weight adjwt;
111 TITLE3 'Raw data listing';
112 run;
NOTE: There were 20 observations read from the data set WORK.BIRDS.
NOTE: The PROCEDURE PRINT printed page 5.
NOTE: PROCEDURE PRINT used (Total process time):
real time 0.00 seconds
cpu time 0.00 seconds
Two sample t-tests
Weight in gms of male & female pheasants
Raw data listing
Adj
Obs sex weight WT
1 Female 1061 1061
2 Female 1065 1065
3 Female 1092 1092
4 Female 1017 1017
5 Female 1021 1021
6 Female 1138 1138
7 Female 1143 1143
8 Female 1094 1094
9 Female 1270 1270
10 Female 1028 1028
11 Male 1293 943
12 Male 1380 1030
13 Male 1614 1264
14 Male 1497 1147
15 Male 1340 990
16 Male 1643 1293
17 Male 1466 1116
18 Male 1627 1277
19 Male 1383 1033
20 Male 1711 1361
113
114 proc ttest data=birds H0=-350; class sex; var weight;
115 TITLE3 'PROC TTEST results specifying a difference';
116 run;
NOTE: There were 20 observations read from the data set WORK.BIRDS.
NOTE: The PROCEDURE TTEST printed page 6.
NOTE: PROCEDURE TTEST used (Total process time):
real time 0.00 seconds
cpu time 0.00 seconds
Two sample t-tests
Weight in gms of male & female pheasants
PROC TTEST results specifying a difference
The TTEST Procedure
Statistics
Lower CL Upper CL Lower CL
Variable sex N Mean Mean Mean Std Dev Std Dev
weight Female 10 1038.1 1092.9 1147.7 52.709 76.63
weight Male 10 1391 1495.4 1599.8 100.36 145.9
weight Diff (1-2) -512 -402.5 -293 88.053 116.53
Statistics
Upper CL
Variable sex Std Dev Std Err Minimum Maximum
weight Female 139.9 24.232 1017 1270
weight Male 266.36 46.138 1293 1711
weight Diff (1-2) 172.33 52.115
T-Tests
Variable Method Variances DF t Value Pr > |t|
weight Pooled Equal 18 -1.01 0.3271
weight Satterthwaite Unequal 13.6 -1.01 0.3313
Equality of Variances
Variable Method Num DF Den DF F Value Pr > F
weight Folded F 9 9 3.63 0.0686
117 proc ttest data=birds; class sex; var adjwt;
118 TITLE3 'PROC TTEST results on adjusted values';
119 run;
NOTE: There were 20 observations read from the data set WORK.BIRDS.
NOTE: The PROCEDURE TTEST printed page 7.
NOTE: PROCEDURE TTEST used (Total process time):
real time 0.00 seconds
cpu time 0.00 seconds
NOTE: SAS Institute Inc., SAS Campus Drive, Cary, NC USA 27513-2414
NOTE: The SAS System used:
real time 0.59 seconds
cpu time 0.24 seconds
Two sample t-tests
Weight in gms of male & female pheasants
PROC TTEST results on adjusted values
The TTEST Procedure
Statistics
Lower CL Upper CL Lower CL
Variable sex N Mean Mean Mean Std Dev Std Dev
AdjWT Female 10 1038.1 1092.9 1147.7 52.709 76.63
AdjWT Male 10 1041 1145.4 1249.8 100.36 145.9
AdjWT Diff (1-2) -162 -52.5 56.989 88.053 116.53
Statistics
Upper CL
Variable sex Std Dev Std Err Minimum Maximum
AdjWT Female 139.9 24.232 1017 1270
AdjWT Male 266.36 46.138 943 1361
AdjWT Diff (1-2) 172.33 52.115
T-Tests
Variable Method Variances DF t Value Pr > |t|
AdjWT Pooled Equal 18 -1.01 0.3271
AdjWT Satterthwaite Unequal 13.6 -1.01 0.3313
Equality of Variances
Variable Method Num DF Den DF F Value Pr > F
AdjWT Folded F 9 9 3.63 0.0686