June 1976 Landsat Image Depicting Three APU's Located 1n 
the Texas and Oklahoma Panhandles 
Figure 3. 
  
    
  
  
   
    
   
  
   
  
   
  
  
  
  
   
throughout the Great Plains. Crop Reporting Districts (CRD's) 
were used as the sampling base. These districts are political 
subdivisions and do not reflect true differences in production 
of agricultural commodities d::» to natural phenomenon. Each 
segment was analyzed during the crop year to enable estima- 
tion of Great Plains wheat production. The 601 sample segments 
were an oversample which necessitated the use of additional 
time and resources for data analysis. 
In 1976, the Great Plains area was resampled using APU's as 
the sampling base. The number of sample segments decreased 
to 487, which reduced the data load by 23 percent. 
b. Improved Yield Homogeneity. During 1975 and 1976, yield 
computations were based on CRD's. This inherently resulted 
in large variances for yield estimation. A study was con- 
ducted in Kansas to determine if APU's increased yield 
homogeneity. County yields for each partition were obtained 
over a 19-year period, starting with 1956. The variability of 
county yields without APU's was 142 percent higher than that 
within APU's, indicating that APU's do divide the state into 
regions where county yields are homogeneous. An analysis 
was done to compare the gain in efficiency between APU's and 
CRD's. APU's had a relative gain of 41 percent, which shows 
that APU's are more homogeneous than CRD's. 
  
c. Mheat/Small Grain Confusion. A major problem in the 
LACIE is separating wheat from other small grains. When 
analyzing a sample segment, it is extremely valuable to have 
cognizance of which small grains are grown in the area and 
whether or not wheat is the major crop. 
  
Each APU was categorized according to the percent wheat, 
type of wheat, and the other small grains. Oklahoma is 
selected to illustrate the results. Table ] lists the 
information applicable to the APU's in Oklahoma. 
Figure 4 is a map of Oklahoma which contains country, CRD, 
and the APU 7 boundary lines. The percent wheat is plotted 
for several counties. Note the drastic differences in yields 
for those counties which are separated by the APU boundary 
lines. These lines were develcped along natural boundaries 
as discussed in the development of APU's. From the LACIE 
Stnadpoint, the area within APU 7 has similar growing con- 
ditions, thus making it easier to analyze any sample segment 
falling within this APU. This would not be the case if this 
area was subdivided along political subdivisions.