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2015 Assessment of the BRB-3 for Compliance with Phase 111 Performance Standards <br />COVER <br />As described above, in 2015, sample adequacy based on all -hit allowable herbaceous cover values was <br />achieved for BRB-3 and each of the extended reference areas except the Steep Mountain Brush ERA. <br />Thus, in consideration of the lack of a sample size sufficient to detect a 10 percent reduction in the mean <br />with 90 percent confidence (i.e. sample adequacy), the upper limit of the possible values of the true mean <br />(with a sample size of 16) was determined. This can be done in either of two ways. <br />1) Confidence Intervals <br />C.I. _ (sNn)'t = (12.6N16) x 1.341 = 4.22 <br />27.3 + 4.22 = 31.6% <br />2) Sample Adequacy Expression <br />52t <br />N=d2V <br />d = �((s2t)/(x2N)) _ �((12.62 x 1.3412)/(27.32 x 16)) = 0.154 <br />X + d = 27.3 + (27.3'0.154) = 31.6% <br />31.6 percent allowable all -hit herbaceous cover represents the highest possible value of the true mean for <br />the Steep Mountain Brush ERA. <br />Calculation of 90 percent of the cover performance standard appropriate for 2015 sampling using the <br />highest possible value for the Steep Mountain Brush Reference Area component is demonstrated below. <br />Aspen Reference Area Allowable All -Hit Herbaceous Cover' = 74.3% <br />Mountain Brush Reference Area Allowable All -Hit Herbaceous Cover' = 54.2% <br />Sagebrush Reference Area Allowable All -Hit Herbaceous Cover' = 41.3% <br />Steep Mountain Brush Reference Area Allowable All -Hit Herbaceous Cover' =31.6% <br />Western Wheatgrass/ Alkali Sagebrush Reference Area Allowable All -Hit Herbaceous Cover' = 40.5% <br />'Herbaceous cover adjusted by subtracting noxious weeds and annual/biennial plant cover in excess of 10% of the remainder <br />23 <br />