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Sample Adequacy <br />A summary of sample adequacy calculations for the parameters of cover, total production, and <br />woody plant stem density is presented in Table 19 (Appendix 1). Sample adequacy was <br />achieved for all sample parameters. <br />In 1996, Rocky Mountain Reclamation completed 182 shrub density transects and calculated an <br />' Nm;,, of 179 belt transects in the Pre-1986 Reclamation Area. Achievement of sample adequacy <br />for biomass production sampling in this area in 1996 required 60 samples to reach an Nm;,, of 58. <br />In 1999, ESCO Assoc. used atwo-stage sampling design for all shrub density and biomass <br />production sampling. Use of this two-stage sampling design minimized sample variance and <br />facilitated the achievement of sample adequacy with fewer total samples. In accordance with the <br />two-stage design detailed in the section, "Statistical Methods: Statistical Design", each monitoring <br />unit was divided into twenty primary sampling units. The size of the primary units varied <br />' according to the size of the monitoring unit. <br />Of the twenty primary units, twelve for randomly selected for sampling. Twelve was chosen as a <br />' sample size that was short of expending the effort to sample everything, yet would provide an <br />ample number to calculate variance. The sampling fraction of the primary units (f,= n/N) was <br />12/20. Within each primary unit, three (3) sample locations were selected. At each sample <br />location, a 0.5 square meter biomass production sample and a 100 square meter shrub density <br />sample were taken as was described in the sections, "Methods: Total Annual Production <br />Sampling, and "Methods: Shrub Density Sampling". The sampling fraction within each primary <br />unit (f2 = m/M) was equal to 3/M in all monitoring units. That is, within each of the twelve primary <br />units selected for sampling there was a potential of M different 100 square meter sample <br />locations. The value of M varied according to the size of the monitoring unit and is detailed in the <br />following table• _ <br />' Potential Number of Samples within Each Primary Unit <br />Area (M) <br />Pre-1986 Reclamation 70.79 <br />' 1995 Reclamation 117.90 <br />1996 Reclamation 39.10 <br />Alkali Sagebrush Reference Area 7.66 <br />' Sagebrush-Grass Reference Area 29.02 <br />Sagebrush-Gravel Reference Area 38.34 <br />' Variance was calculated in the fashion described in the section, "Statistical Methods: Sample <br />Variance for Sample Adequacy Calculations". <br />' 1-f~ 1-f2 <br />Vy ~ S,2 + S22 <br />' n mn <br />19 <br />