Chapter 3 Data and Analysis Methods
3.1 Variable Explanation
3.1.3 Explanatory Variables
Three groups of explanatory variables are categorized as economic/social variables, biomass availability variables, and transportation-related variables. A total 119 explanatory variables were used in this study (see Table 1 for a detailed explanation of units, collection levels, and variable types). For example, “Population Density” is a continuous variable standing for population density in the unit of people per square mile in each 5-digit ZCTA. Models of the Group I and Group III biomass-using facilities use the first 116 explanatory variables in Table 3- 1. Models of Group II biomass-using facilities include the last additional three explanatory variables in Table 3-1 for the consideration of their potential impacts on the locations of Group II biomass-using facilities. The three explanatory variables are continuous and represent the
number of primary wood processing mills, the number of secondary wood processing mills, and the number of other mills in each 5-digit ZCTA, labeled as “Primary_Mill_No”,
25
Table 3-1 Explanatory variables for three groups of biomass-using facilities
Variable name Variable
Type
Collection
level Unit Explanation
Population Continuous 5-digit
ZCTA People Population in each 5-digit ZCTA
Population_Density Continuous 5-digit
ZCTA
People/ miles
Population density in each 5-digit ZCTA
Employment Continuous 5-digit
ZCTA People
Employed person in all industries in each 5-digit ZCTA
Median_Family_Income Continuous 5-digit
ZCTA Dollar
Median of family income in 1999 in each 5-digit ZCTA
Income_Index Continuous 5-digit
ZCTA
Dollar/p eople
Median of family income in 1999 per employed person in each 5-digit ZCTA
Sqmiwater Continuous 5-digit
ZCTA Mile
2
Water area within 5-digit ZCTAs Barley_RES_Qty
Continuous County Dry tons
Agricultural materials left in an agricultural field after the crop has been harvested. Residues in every county are from Barley Straw, Corn Stover for silage and for grain, Oat Straw, Sorghum Straw, Wheat All Straw, and Wheat Winter All Straw.
Corn_RES_Qty Oat_RES_Qty Sorghum_RES_Qty WheatAll_RES_Qty WheatWinter_RES_Qty Barley_RES_HC
Continuous County Dollar/d
ry tons
Harvesting costs of agricultural residues in each county. Agricultural residues are from Barley Straw, Corn Stover for silage and for grain, Oat Straw, Sorghum Straw, Wheat All Straw, and Wheat Winter All Straw.
Corn_RES_HC Oat_RES_HC Sorghum_RES_HC WheatAll_RES_HC WheatWinter_RES_HC Barley_40_MCost
Continuous ZIP Code Dollar/
mile
Marginal trucking cost of total Barley Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Barley_80_MCost Barley_120_MCost Barley_160_MCost Corn_40_MCost
Continuous ZIP Code Dollar/
mile
Marginal trucking cost of total Corn Stover residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Corn_80_MCost Corn_120_MCost Corn_160_MCost Oat_40_MCost
Continuous ZIP Code Dollar/
mile
Marginal trucking cost of total Oat Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Oat_80_MCost Oat_120_MCost Oat_160_MCost
26 Table 3-1 (Continued)
Variable name Variable
Type
Collection
level Unit Explanation
Sorghum_40_MCost
Continuous ZIP Code Dollar/
mile
Marginal trucking cost of total Sorghum Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Sorghum _80_MCost Sorghum _120_MCost Sorghum _160_MCost WheatAll_40_MCost
Continuous ZIP Code Dollar/
mile
Marginal trucking cost of total Wheat All Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
WheatAll_80_MCost Wheat All_120_MCost Wheat All_160_MCost WheatWinter_40_MCost
Continuous ZIP Code Dollar/
mile
Marginal trucking cost of total Wheat Winter All Straw residues within a 40- mile, 80-mile, 120-mile, and 160-mile haul distances.
WheatWinter_80_MCost WheatWinter_120_MCost WheatWinter_160_MCost Barley_40_TCost
Continuous ZIP Code Dollar/
mile
Total trucking cost of total Barley Straw residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Barley_80_TCost
Barley_120_TCost Barley_160_TCost Corn_40_TCost
Continuous ZIP Code Dollar/
mile
Total trucking cost of total Corn Stover residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Corn_80_TCost
Corn_120_TCost Corn_160_TCost Oat_40_TCost
Continuous ZIP Code Dollar/
mile
Total trucking cost of total Oat Straw residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Oat_80_TCost
Oat_120_TCost Oat_160_TCost Sorghum_40_TCost
Continuous ZIP Code Dollar/
mile
Total trucking cost of total Sorghum Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Sorghum_80_TCost Sorghum_120_TCost Sorghum_160_TCost WheatAll_40_TCost
Continuous ZIP Code Dollar/
mile
Total trucking cost of total Wheat All Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
WheatAll_80_TCost WheatAll_120_TCost WheatAll_160_TCost
27 Table 3-1 (Continued)
Variable name Variable
Type
Collection
level Unit Explanation
WheatWinter_40_TCost
Continuous ZIP Code Dollar/
mile
Total trucking cost of total Wheat Winter All Straw residues within a 40- mile, 80-mile, 120-mile, and 160-mile haul distances.
WheatWinter_80_TCost WheatWinter_120_TCost WheatWinter_160_TCost Barley_40_ACost
Continuous ZIP Code Dollar/
mile
Average trucking cost of total Barley Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Barley_80_ACost Barley_120_ACost Barley_160_ACost Corn_40_ACost
Continuous ZIP Code Dollar/
mile
Average trucking cost of total Corn Stover residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Corn_80_ACost Corn_120_ACost Corn_160_ACost Oat_40_ACost
Continuous ZIP Code Dollar/
mile
Average trucking cost of total Oat Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Oat_80_ACost Oat_120_ACost Oat_160_ACost Sorghum_40_ACost
Continuous ZIP Code Dollar/
mile
Average trucking cost of total Sorghum Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
Sorghum_80_ACost Sorghum_120_ACost Sorghum_160_ACost WheatAll_40_ACost
Continuous ZIP Code Dollar/
mile
Average trucking cost of total Wheat All Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
WheatAll_80_ACost WheatAll_120_ACost WheatAll_160_ACost WheatWinter_40_ACost
Continuous ZIP Code Dollar/
mile
Average trucking cost of total Wheat Winter All Straw residues within a 40- mile, 80-mile, 120-mile, and 160-mile haul distances.
WheatWinter_80_ACost WheatWinter_120_ACost WheatWinter_160_ACost Barley_40_TQty
Continuous ZIP Code Dollar/
mile
Cumulative quantity of Barley Straw residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Barley_80_ TQty
Barley_120_ TQty Barley_160_ TQty
28 Table 3-1 (Continued)
Variable name Variable
Type
Collection
level Unit Explanation
Corn_40_TQty
Continuous ZIP Code Dollar/
mile
Cumulative quantity of Corn Stover residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Corn_80_ TQty
Corn_120_ TQty Corn_160_ TQty Oat_40_ TQty
Continuous ZIP Code Dollar/
mile
Cumulative quantity of Oat Straw residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Oat_80_ TQty
Oat_120_ TQty Oat_160_ TQty Sorghum_40_ TQty
Continuous ZIP Code Dollar/
mile
Cumulative quantity of Sorghum Straw residues within a 40-mile, 80-mile, 120- mile, and 160-mile haul distances. Sorghum_80_ TQty
Sorghum_120_ TQty Sorghum_160_ TQty WheatAll_40_ TQty
Continuous ZIP Code Dollar/
mile
Cumulative quantity of Wheat All Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
WheatAll_80_ TQty WheatAll_120_ TQty WheatAll_160_ TQty WheatWinter_40_ TQty
Continuous ZIP Code Dollar/
mile
Cumulative quantity of Wheat Winter All Straw residues within a 40-mile, 80- mile, 120-mile, and 160-mile haul distances.
WheatWinter_80_ TQty WheatWinter_120_ TQty WheatWinter_160_ TQty
RailroadAvailability Ordinal ZIP Code
Railroad accessible index ranked by four railroad companies as N/A, 1, 2, 3, and 4. “N/A” means this ZIP Code has no railroad; “1” means one out of four railroad companies ranks this ZIP Code as having railroad access and so on. Larger number means that the ZIP Code has more railroad access.
No_ports Continuous 5-digit
ZCTA Port
Number of water ports in each 5-digit ZCTA
Primary_Mill_No Continuous 5-digit
ZCTA Mill
Number of primary wood processing mills in each 5-digit ZCTA
Secondary_Mill_No Continuous 5-digit
ZCTA Mill
Number of secondary wood processing mills in each 5-digit ZCTA
29 Table 3-1 (Continued)
Variable name Variable
Type
Collection
level Unit Explanation
Other_Mill_No Continuous 5-digit
ZCTA Mill
Number of other mills in each 5-digit ZCTA. Other mills include forestry
companies, logging mills, and
companies that provide equipment and supplies, such as logging machine rental companies (Perlack et al. 2005).