APPENDIX 1. DATA RELIABILITY 



4 



The sampling errors presented in tables 48 and 49 are calculated for one 

 standard error — the 67 percent confidence level. In other words, in 

 two-out-of-three times, the actual value will be within the specified confidence 

 interval. Individual cells within tables should be used with caution. Some of 

 the data presented in other tables are based on small sample sizes and as a 

 result have high sampling errors. For example, the percent error for indi- 

 vidual forest type acreages within the commercial timberland total will all have 

 a higher error than 1.8 percent (see table 48). 



Table 48. Forest land area and associated sampling error percentages for 

 Working Circle 3. 



Item Softwood Types Hardwood Types All Types 



Acres Error Acres Error Acres Error 



Commercial 



timberland 1,102,860 ±1.9% 77,140 ±19.7% 1,180,000 ±1.8% 



Other 



timberland 51,205 ±20.6% 14,119 ±41.3% 65,324 i:18.2% 



Table 49. Net volume, net annual growth, and annual mortality on commercial 

 timberland, with associated sampling error percentages for 

 Working Circle 3. 



Item Softwood Species Hardwood Species All Species 



Volume Error Volume Error Volume Error 

 Volume : 



Growing stock 1,662,066 ±4.1% 94,902 ±31.7% 1,756,968 ±4.1% 

 (thousand cubic feet) 



Sawtimber 4,408,044 ±4.9% 271,281 ±39.1% 4,679,326 ±5.0% 

 (MBF Scribner) 



Net Growth: 



Growing stock 35,108 ±8.7% 2,016 ±28.0% 37,124 ±8.3% 



(thousand cubic feet) 



Sawtimber 99,380 ±7.6% 7,838 ±29.8% 107,218 ±7.3% 



(MBF Scribner) 



Mortality: 



Growing stock 5,297 ±15.6% 218 ±58.2% 5,515 ±15.2% 



(thousand cubic feet) 



Sawtimber 12,989 ±21.1% 572 ±89.8% 13,562 ±20.6% 



(MBF Scribner) 



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