954 
Journal of Agricultural Research 
Vol. XXXI, No. 10 
In many experiments and probably in the majority of specific 
instances it does not matter which parallelism is used in the inter¬ 
pretation of results, since the application of Student’s method to 
either will establish significance or nonsignificance in the same direc¬ 
tion. In the foregoing examples it has been shown that the appli¬ 
cation of Student’s method to paired gains may give odds that will 
not support the conclusion drawn when the method is applied to 
the corresponding pairs of yields, this being the way the method has 
been generally applied (2; 6, p. 10; 7, p. 22; 8; 9; 10; If p. 6 ). More¬ 
over, when the interpretation of fertilizer results is based on the 
S arallelism of yields it may even be shown that fertilizer treatment 
1, for example, is more effective than fertilizer treatment Y; but 
that when the interpretation of the results is based on the correspond¬ 
ing pairs of gains effected odds may indicate just about as high a 
degree of certainty that fertilizer treatment Y is the more effective. 
Tins may be illustrated by the published results obtained with 
wheat on plots Nos. 15 and 3 2 in the potato-wheat-clover rotation 
at Wooster for the period 1895 to 1912, inclusive, which follow 
(f 3, 4 and Table V): 
Table V. — Student’s method applied to wheat yields in potato-wheat-clover rotation 
at Wooster , Ohio 
Year 
Actual yields 
Differ¬ 
ence in 
yields 
No. 15 
over 
No. 32 
Devi¬ 
ation 
from 
1.49 
(D) 
D2 
Gains effected 
Differ¬ 
ence in 
Devi¬ 
ation 
from 
2.16 
(D) 
D2 
Plot 
No. 15° 
Plot 
No. 32 b 
Plot 
No. 32 
Plot 
No. 15 
gains 
No. 32 
over 
No. 15 
Bush. 
Bush. 
Bush. 
Bush . 
Bush. 
Bush. 
1895-... 
(«) 
1896.. 
(<) 
1897_ 
4100 
39.17 
4.83 
3.34 
11.16 
6.45 
6.56 
-0.11 
2.27 
5.15 
1898 . 
37.42 
32.25 
5.17 
3.68 
13.54 
8.52 
13.73 
—5.21 
7.37 
54. 32 
1899___ 
35.07 
34.58 
1.09 
.40 
.16 
10.69 
7.87 
2.82 
.66 
.44 
1900—.. 
48.00 
44.91 
3.09 
1.60 
2.56 
13.91 
5.59 
8.32 
6.16 
37.95 
1901.—.— 
29.83 
28.33 
1.50 
.01 
.00 
7.39 
6.55 
.84 
1.32 
1.74 
1902_ 
52.25 
49.33 
2.92 
1.43 
2.05 
17.78 
15.78 
2.00 
,16 
.03 
1903___ 
38.67 
38.17 
.50 
.99 
.98 
13.89 
9.20 
4.69 
2.53 
6.40 
1904_ 
27.50 
29.21 
-1. 71 
3.20 
10.24 
7.43 
13.43 
-6.00 
8.16 
66. 59 
1905... 
34.58 
30.13 
4.45 
2.96 
8. 76 
11.46 
11.41 
.05 
2.11 
4.45 
1906__ 
50.71 
49.17 
1.54 
.05 
.00 
12.49 
6.16 
6.33 
4.17 
17. 39 
1907__- 
35.00 
40.83 
-5.83 
7.32 
53.58 
6.22 
.44 
5.78 
3.62 
13.10 
1908... 
48.50 
49.50 
-1.00 
2.49 
6.20 
17.99 
12.06 
5.93 
3. 77 
14.21 
1909__— 
44.87 
42.75 
2.12 
.63 
.40 
8.68 
3.32 
5.36 
3.20 
10.24 
1910—... 
33.54 
34.12 
-.58 
2.07 
4.28 
9.10 
11.72 
-2.62 
4.78 
22.85 
1911_—__— 
39.25 
36.33 
2.92 
1.43 
2.04 
17.94 
14.36 
3.58 
1.42 
2.02 
1912-.. 
13.83 
11.04 
2.79 
1. 30 
1.69 
4.82 
2.08 
2.74 
.58 
.34 
Mean_ 
38. 35 
36.86 
1. 49 
7.35 
10.92 
8.77 
2.16 
16.08 
o-=2. 7 
<r=4 .01 
Z= 0. 55. Z= 0. 54. 
P= ±0.9734. P= ±0.9715. 
Odds=37 to 1. Odds=34 to 1. 
° Fertilizer treatment consists of 32 pounds of nitrate of soda, 480 pounds of acid phosphate, and 300 pounds 
of muriate of potash per acre applied for potatoes only. 
b Fertilizer treatment consists of 16 tons of barnyard manure applied for wheat. 
«No yields are reported for plot No. 32 for 1895 and 1896. 
When Student’s method of interpretation is applied to the actual 
yields obtained on plots Nos. 15 and 32 certainty is established in 
terms of odds of 37 to 1 that the complete chemical fertilizer applied 
for potatoes, on plot No. 15, is more effective in increasing the yields 
of wheat (the crop following potatoes) than 16 tons of manure 
