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2.3 SAMPLE NUMBERS/SAMPLE ADEQUACY <br />For the purposes of this study, total vegetation cover sampling of the reclaimed areas and <br />extended reference area was undertaken to sample adequacy with a minimum of fifteen (15) <br />samples. <br />Parameter sample adequacy testing occurred at the one-sided 90% confidence level. <br />Comparisons between sample mean parameter values and the revegetation success standard <br />assume that the sample mean value accurately represents the population mean in all cases. <br />The following formula was used for sample adequacy calculations: <br />nmin = <br />(t)z (s)2 <br />(d Xbar)2 <br />where: nmin = minimum sample size <br />s = sample standard deviation <br />t = the Student's t distribution value at the 90% level (one-sided) <br />d = percent acceptable deviation from the mean (10%) <br />Xbar = sample mean <br />2.4 STATISTICAL ANALYSIS <br />Statistical analysis for the revegetation success criterion of total vegetation cover is required if <br />the value of the sample mean from the reclaimed area is less than 90 percent of the value of <br />the final revegetation success criterion for total vegetation cover. The 2020 reclaimed areas <br />sample mean for total vegetation cover was greater than the corresponding revegetation <br />success criterion (the total herbaceous cover mean from the extended reference area); therefore <br />no statistical analysis was required. A statistical analysis is not required for the evaluation of <br />species composition. <br />2.5 SPECIES IDENTIFICATION AND VERIFICATION <br />Species identification was accomplished in the field through the use of plant identification keys <br />(Harrington, 1954, Weber, 1990; Whitson, 1987; Zimdahl, 1990, Stubbendieck, et al, 1995). <br />In cases where plant identification was inconclusive in the field, voucher specimens were <br />pressed for lab identification and photographed, and verified by Mr. Tim Hogan and Ms. Dina <br />Clark of the University of Colorado, Boulder Herbarium. <br />Oxbow Mining, LLC Elk Creek Mine Page 5 <br />2020 Phase 11 Bond Release Vegetation Report <br />