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i ~ <br />• <br />l I <br />Gregg Squire - 3 - November 25, 1985 <br />If the production on the revegetated area 15 greater to or equal to 90 percent <br />of the production on the weighted reference areas the revegetatlon will be <br />judged successful with respect to production. <br />If the absolute production value from the revegetated area is less than the <br />quantity (.9 Xr) a statistical test is warranted to determine whether the <br />absolute production is within acceptable statistical confidence limits of the <br />standard (t.e., with 80% confidence, is Xm > Xr). The statistical measure <br />to be used will be a students t-test, taking the form: <br />t I xm - Rrl <br />SXm-Xr <br />or computationally: <br />t Rm-Rrl l <br />Jsp ( Nm t Nr 1 <br />I\ Nm Nr <br />Nhere t a measure of the difference between <br />the production means <br />Rm = the average production from the <br />revegetated area <br />Ar the average production from the <br /> weighted reference areas <br />Nm the number of samples from the <br /> revegetat ed areas <br />Nr = the number of samples from the <br /> reference areas <br />Sp = the pooled variance represented: <br />Sp = (Nm-1) Sm 2 « (Nr-1) Sr 2 <br />(Nm-1 ) + (Nr-1) <br />If the calculated t value exceeds the table t (oC = 0.2(1), (Nm+N r+2) <br />then the null hypothesis will be rejected and it will be concludes th~t the <br />revegetated site has not met the production success criteria. <br />from Steel, R.G.D. and J. H. Torrie. 1980. Principles and Procedures of <br />Statistics. McGraw-Hill, New York 633p. <br />/1jc <br />5126E <br />