Preliminary office work (cont.) 



Important steps in the operation 



Key points 



6. Using accuracy, coefficient of 

 variation, number of trees in 

 sale, correlation coefficient, 

 and cost ratio, deteimlne sample 

 size for each species and 

 stratum 



Refer to Figure 2, page 22 of this 

 publication, or to formulae in 

 Appendix VIII o 



If no check scaling is contemplated, 

 that is, if the sample is for the 

 purpose of estimating tree measured 

 volume instead of scaled volume, the 

 sample size is determined from Fig- 

 ure 1, page 7o Correlation coeffici- 

 ent and cost ratio need not be 

 determined for use of this graph. 



7. Calculate sampling ratio for 

 each species and stratum 



Divide total number of trees in a 

 species or stratum group by sample 

 size. Round off to nearest vdaole 

 numbero 



8. Prepare field sampling forms 



a . 



Determine number of "tree 

 count numbers" needed in 

 each section of form 



b. 



c. 



Choose one number at random 

 from each sampling rate 

 interval 



Encircle numbers chosen for 

 sample trees 



See sample form 3 "Sample Tree 

 Measurement Tally Sheet" on the 

 following pagOo Prepare separate 

 forms for each species and stratum 

 to be sampled. Be sure an adeq.ua te 

 supply is prepared o 



Found by multiplying sampling ratio 

 by 4 (because four spaces are pro- 

 vided in each section of the sample 

 form) . Gross out any additional 

 numbers not needed. 

 For example, a 1 in 5 rate would 

 use only 20 numbers, wtiile a 1 in 

 10 rate would use all 40 nuiaberSo 

 Rates less than 1 in 10 can be used, 

 but all the spaces for recording tree 

 measurements in each section of the 

 form vjill not be filled., For example, 

 a 1 in 20 ratio would fill only tv;o 

 spaces in each section, but would use 

 all 40 numbers. 



If the sample form shorn here does 

 not apply well to the conditions en- 

 countered, forms can be made up with 

 appropriate spaces and "tree count 

 numbers" in each section., 



Use random numbers as described in 

 Appendix X<. 



-34- 



