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• Note that the vegetation types in question all have greater than 15 percent <br />relative cover by woody species and so were deemed "woody" for statistical <br />purposes. <br />The statistical comparability between reference and affected area vegeta- <br />tion cover, herbaceous production, and shrub density was evaluated using <br />methods recommended by CMLRD. For each pair of reference and affected areas, <br />a t value is calculated as follows for cover, production, and density: <br />t - xA - xR <br />s- _ <br />xA xR <br />sZ sz <br />where s? - _ P P <br />xA - xR nA + nR <br />dASA + dRSR <br />and sP = d + d <br />A R <br />xA = affected area mean <br />xR = reference area mean <br />z <br />• sxA - xR = the variance of the difference between the means <br />sp = pooled variance <br />nA = affected area sample size <br />n = reference area sample size <br />R <br />sA = affected area sample variance <br />sR = reference area sample variance <br />dA = degrees of freedom, affected area <br />dR = degrees of freedom, reference area <br />The t-value so calculated is comprised of a two tailed t-value at 95% <br />confidence (a = 0.051 for (n + n 1-1 degrees of freedom from a statistical <br />table. If the calculated t valueRis less than or equal to the table t value, <br />the reference and affected areas are deemed "comparable" for the parameter <br />being considered. <br />• <br />-5- <br />