1 



APPENDIX — ^ADEQUACY OF DATA 



661 



ments of probability sampling were met and sam- 

 pling errors were calculated for the major items of 

 data. Sampling error goals were set for each re- 

 gion and were met satisfactorily. For the United 

 States and Coastal Alaska as a whole, the sam- 

 pling error of the estimate of total private operat- 

 ing area is 2.0 percent (table 84). Errors of the 

 estimates of private operating area by productivity 

 class range from 2.7 to 5.9 percent. Sampling 

 errors of the public ownership data have not been 

 calculated because coverage was generally 100 

 percent. 



Figure 3 provides a means of appro.ximating the 

 sampling errors of further breakdowns of the items 

 given in table 84. The application of figure 3 

 corresponds to that previously used for figure 1. 

 For a particular breakdown, find the smallest unit 

 of which it is a part and for which the sampling 

 error is given in table 84, determine the percent of 

 area which the breakdown represents, and read 

 the corresponding factor from figure 3. The prod- 

 uct of this factor and the sampling error of the 

 whole is the approximate sampling error of the 

 breakdown. 



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3 4 5 6 8 10 20 30 40 50 60 80 100 

 PERCENT OF AREA OR NUMBER OF OWNERS IN A BREAKDOWN 



Figures. — Ratioof standard error of an area or number-of-owner breakdown to standard error of a total based on 

 the survey of productivity of recently cut lands. (A) Applies to area and number-of-owner statistics for 

 ownerships of less than 5,000 acres in California and the East. (B) Applies to area statistics of ownerships 

 less than 5,000 acres in Pacific Northwest, Northern Rocky Mountain, and Southern Rocky Mountain Regions. 

 Applies also to area statistics for ownerships of 5,000 to 50,000 acres. 



