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4-3B <br />where nmin = the minimum adequate number of samples required <br />• s2 = sample variance <br />t = two-tailed t distribution value at the 908 <br />confidence (1.64) or the 808 confidence level <br />(1.28) <br />d = desired limits of detection (0.1 or 108) <br />x = sample mean <br />following collection and analysis of data the comparability of <br />the reference area (Greasewood Shrubland only) and analogous <br />affected areas was evaluated statistically at the 95 percent <br />confidence level for cover and production with the formula <br /> <br /> <br /> <br /> <br />x <br />- x <br />l 2 <br />where xl = mean cover or production for the affected area <br />• x2 = mean cover or production for the reference area <br />t = a t-statistic value, which varies depending on <br />desired level of confidence and sampling size <br />si = the variance of cover or production for the <br />affected area <br />s2 = the variance of cover or production for the <br />reference area <br />nl = sample size in the affected area <br />n2 = sample size in the reference area <br />When I xl - x2 I is less than or equal to the other calculated <br />value, the affected area and reference area are considered com- <br />parable for the purpose of evaluating reclamation success. <br />2 2 <br />sl + s2 <br />t nl n2 <br />• <br />