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2.5 Sample Adequacy Determination and Testing for Success <br />Direct comparison testing was utilized as the preferred success testing protocol for cover, <br />production, and woody plant density in the grassland and riparian areas. For this procedure, collection of <br />an "adequate" siimple (where nm;,, <_ n) is necessary for all sample means used for comparison. <br />Sampling in these areas continued until sampling adequacy (nm;n) had been attained in accordance with <br />the promulgated (~olorado guideline (April 18, 1995) formula for sample adequacy when statistical testing <br />is not required, as. follows: <br />nmin = ~t2s2) ~ (dx)2 <br />Where: n =the number of actual samples collected with a minimum of 15 in each unit; <br />f =the one-tailed value from the t distribution for 90% confidence with n-1 degrees <br />of freedom; <br />s2 -the variance of the estimate as calculated from the initial samples; <br />.z' =the mean of the estimate as calculated from the initial samples; <br />d = degree of required precision (0.1 for cover and production, 0.15 for woody plant <br />density) <br />Testing for cover and production success employs a direct comparison with 90% of a statistically <br />adequate sample mean from the appropriate reference area, whereas testing for woody plant density <br />and diversity is a direct comparison with established standards (given adequate sampling for woody plant <br />density). When these tests are successful for two consecutive years for each variable of the revegetated <br />community, and the diversity numerical standards have also been met for each year, then conditions for <br />final bond release have been met. <br />CEDAR CREEK ASSC)GIATES, Inc. Page 8 Blue Ribbon Mine -Phase III <br />Bond Release Evaluation - 2007 <br />