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2.5 Sample Adequacy Determination and Testing for Success <br />Reverse-null hypothesis testing was utilized as the preferred testing protocol for cover, production, <br />and woody plant density in the riparian area. For this procedure, collection of an "adequate" sample <br />(where nmi" <_ n) is not necessary as it is in the operator's best interest to sample until a "tight" estimate <br />of the mean is obtained (i.e., sampling should continue until the variance is "narrowly" defined). <br />Sampling in these areas continued until: 1) a minimum of samples had been collected or 2) sampling <br />adequacy (nm~n) had been attained in accordance with the promulgated Colorado guideline (April 18, <br />1995) formula for sample adequacy when statistical testing is not required, as follows: <br />nmin = ~t~sZ) ~ (o.lx)2 <br />Where: n =the number of actual samples collected with a minimum of 15 in each unit; <br />t = the one-tailed value from the t distribution for 90% confidence with n-1 degrees <br />of freedom; <br />sZ ° the variance of the estimate as calculated from the initial samples; <br />s =the mean of the estimate as calculated from the initial samples <br />In the "classical" null hypothesis test, rejection of H° means failure as the hypothesis being <br />tested is that the reclaimed area variable is greater than or equal to 90% of the reference area or <br />standard. However, in the reverse null test, rejection of H° means success as the hypothesis being <br />tested is that the reclaimed area variable is less than or equal to 90% of the reference area or standard. <br />Therefore, once a sample has been collected from both the target area of interest and the reference area <br />(or standard), the means and variances (x and sz) of those samples will be utilized for testing <br />revegetation success or failure. Testing will occur as follows: <br />r~=xSQ Where: C!=90%ofthe Standard <br />x =Sample mean of the reveg data <br />s =Sample Standard Deviation <br />n =Sample Size <br />Then if r<> t for t(a=O.l,n-1 d.f.) the test is successful . <br />CEDAR CREEK ASSOCIATES, INC. Page 8 Blue Ribbon Mine - 2006 <br />Phase III Bond Release Evaluation <br />