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<br />• <br />where: <br />k =one-tailed t-value with (n-1) degrees of freedom, a=0.10 <br />sZ =sample variance <br />d = 0.1 (level of precision or desired detectable reduction) <br />x =sample mean <br />Sample Variance for Sample Adequacy Calculations <br /> <br />For one-stage sampling, variance was calculated as the square of the standard deviation (m). <br />For the two-stage sampling of woody plant density, calculation of sample variance for use in the <br />sample adequacy formulas was as follows (Expression 10.10 of Cochran 1977): <br />1-f~ 1-fZ <br />z z <br />Vy = S~ + SZ <br />n mn <br />where: <br />VY =Overall variance of woody plant density data <br />f, = n/N= 15/20 <br />f2 = m/M= 3/607 <br />S,Z =variance among primary unit means ~, <br />S22 =variance among elements within primary units relative to the primary unit means <br />N =total number of primary units that exist within the sampling area and are potentially to be <br />sampled <br />5 <br />