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Sampline Adequacy Determination <br />• Sampling was conducted pursuant to the requirements of Rule 4.15.8, and from this information sample means (x), <br />and sample variances (s) were determined for each plant variable for each community. Enough samples were <br />taken to provide a plant variable estimated to within 10 percent of the true mean (m) with 90 percent confidence for <br />herbaceous and 80 percent confidence for woody communities. Sampling to at least these values constituted an <br />adequate sample. <br />To obtain an adequate sample and estimates of each parameter, the following inequality was met: <br />where: <br />where: <br />nmin < n <br />the actual number of samples taken <br />nmin = (es') <br />(o— 1� <br />= value from a t table (1.28 for woody communities or 1.645 for herbaceous ones) <br />• s2 = sample variance <br />T = sample mean <br />• <br />Reference Area Testine Statistics <br />To provide the basis for reclamation success, TCC has opted to use reference areas pursuant to Rule 4.15.7. To <br />prove that chosen reference areas are statistically equivalent to their corresponding vegetation types with respect to <br />the measured variables, a standard two -tailed t-test of the means with equal variances assumed (Larson 1980) was <br />performed. This test was performed at the alpha =.05 level for differences between means. <br />Because the number of samples taken for each community was not necessarily the same as the number taken for the <br />corresponding reference areas, a weighted tabular t comparison statistic (t,) was calculated as follows: <br />where: <br />ti = (sit/nal)(tal) + 022/n2)(t 2) <br />(SI /ni) + (52 /n2) <br />Subscript I = premine vegetation type parameters <br />Subscript 2 = corresponding reference area parameters <br />to = tabular t value for ni_ l or <br />n2-1 d.f. at the a = .05 level. <br />Permit Renewal No. 3 2.04-53 12/10/98 <br />