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2.3 SAMPLE NUMBERS/SAMPLE ADEQUACY <br />For the purposes of this study, total vegetation cover and total herbaceous production sampling <br />of the post-SMCRA reclaimed areas and extended reference area was undertaken to sample <br />adequacy with a minimum of fifteen (15) 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)2 (s)2 <br />= <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 criteria of total vegetation cover and total <br />herbaceous production is required if the value of the sample mean from the reclaimed areas for <br />either parameter is less than 90 percent of the corresponding mean parameter value from the <br />extended reference area. The 2019 reclaimed area sample means for total vegetation cover and <br />total herbaceous production were greater than the corresponding applicable revegetation <br />success criteria mean values from the extended reference area, therefore no statistical analysis <br />was required. A statistical analysis is not required for the evaluation of 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 verified by Mr. Tim Hogan and Ms. Dina Clark of the <br />University of Colorado, Boulder Herbarium. <br />Oxbow Mining, LLC Elk Creek Mine Page 5 <br />2019 Phase III Bond Kelea5e Po5t-5MCKA Vegetation Report <br />