RELIABILITY AND ADEQUACY OF FARM-PRICE DATA 
45 
'able 23. — Farm prices: Correlation between the farm-price series of wheat, 
cotton, and white potatoes in neighboring States — Continued 
Crop, State, and date 
Number 
of 
reports 
Average prices for 
series 
Standard devia- 
tions for series 
Correla- 
tion co- 
efficient 
00 
X 
Y 
X 
Y 
Wheat, per bushel— Continued. 
Indiana and Illinois — 
1908-1914 
84 
84 
48 
216 
72 
84 
48 
204 
84 
84 
48 
216 
Cents 
95.8 
176.0 
124. 3 
133.3 
11.6 
20.8 
23.7 
18.2 
60.4 
125.0 
78.3 
89.5 
Cents 
93.6 
174.2 
120.1 
130.9 
12.0 
21.8 
24. 2 
18.' 9 
72.0 
137.9 
96.6 
102.3 
Cents 
10.9 
49.2 
25.7 
49.1 
1.98 
9.30 
4.09 
8.15 
22.2 
75.4 
34.7 
59.3 
Cents 
9.1 
50.2 
24.4 
49.4 
2.12 
10.50 
4.23 
8.63 
21.7 
75.6 
38.4 
59.5 
Plus 
0.975 
1915-1921 
.998 
1922-1925 
.994 
1908-1925 
.998 
Cotton, per pound: 
Texas and Georgia— 
1909-1914 
1915-1921 
.976 
.995 
1922-1925 
.984 
1909-1925 
.995 
Potatoes, per bushel: 
Maine and Is evr York— 
1909-1914 
.923 
1915-1921 
.988 
1922-1925 . 
.890 
1909-1925 
.976 
Table 23 also gives a comparison of the average prices and stand- 
ard deviations of the monthly prices in the different periods. The 
New York price of 137. 5 cents was the highest average price of 
wheat for the entire period. The Maryland price of 136.2 cents 
was slightly lower than the New York price, but higher than the 
Pennsylvania price (135.6 cents), the Indiana price (133.3 cents), or 
the Illinois price (130.9 cents) . The price differential between Indiana 
and Illinois was greatest during the last period, when freight rates 
had been increased. The average price is lower as it approaches 
the centers of wheat production for the country. The dispersions of 
these monthly prices were similar in the several States in a given 
period, and it is difficult to say that the dispersion was any greater 
in one State than in any of the others. 
COTTON 
Although Texas and Georgia are not adjoining States and the 
harvest begins earlier in southern Texas than in Georgia, the cor- 
relation during the pre-war period between Texas prices of cotton 
lint per pound and Georgia prices, plus 0.976, is unexpectedly high. 
The correlation during the war period is plus 0.995. The average 
price was slightly higher in Georgia than in Texas; and the dis- 
persion of monthly prices as measured by their standard deviations 
was slightly greater. Figure 7 shows the general trend and close 
correlation of monthly cotton prices for Texas and for Georgia, and 
for purposes of comparison New Orleans spot prices of middling 
cotton. 
POTATOES 
It is difficult to find any two States in which, over a period of 
time, conditions influencing potato prices are even reasonably com- 
parable. Maine is a long distance from market, whereas parts of 
New York State are within easy trucking distance of New York 
City and other large cities. Maine has no section that compares 
with the Long Island potato area of New York, either in nearness 
