-5- 



Sampling Method . INVENT will process point cruises (variable plot) , 

 plot cruises (fixed radius plot), strip cruises, and 100 percent tallies. 

 The sampling method need not be the same for each compartment. When using 

 point or plot sampling, a complete statistical analysis of the reliability 

 of the volume estimates will be calculated only if the data for each point 

 or plot is tallied separately. If only summary data is available, no such 

 statistical analysis can be made. When point sampling, the BAF of the angle 

 used must be specified. When plot sampling, the plot size in acres must be 

 specified. Strip cruises are analysed as a plot cruise where only one large 

 plot is sampled. In this case, the plot size is the total acreage of all 

 strips. There is no statistical analysis of reliability on strip cruises. 

 One hundred percent tallies require no statistical analysis of reliability 

 since all trees in the population have been measured. One hundred percent 

 tallies are also treated as a plot cruise where only one large plot is sampled. 

 Here, however, the plot size is equal to the total acreage of the compartment. 



Tree Height Measurement . Tree height may be measured in feet or sixteen 

 foot logs to the nearest half -log. 



Tree Top Specification . Trees may be measured to a merchantable top or 

 measured by total height. There is also a mixed option where softwoods are 

 measured by total height and hardwoods by merchantable height. As mentioned 

 earlier, form class volume equations for board foot volume are used when 

 merchantable height is specified. 



Were Heights of All Volume Trees Measured ? INVENT allows double sampling 

 for height (Cf. Freese 1962, p. 43). Using this technique, the forester only 

 measures height on a subsample of the trees. INVENT develops a height-dbh 

 relationship from the height trees sampled and uses this relationship to 

 estimate height for the remaining trees. This method must be used with some 

 caution. On at least one-third of the trees in every species, the height 

 should be measured. At least three height trees must be measured for every 

 species within each compartment. An analysis table of the height-dbh relation- 

 ship is printed for each compartment using the option. A warning message is 



