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Cover, production and tree density data were evaluated for sampling <br />adequacy using the statistical formula: <br />N ' 2 (s z) 2 <br />m~ (d x) 2 <br />where: <br />= mini.nnmi number of cover quadrats, production exclosures <br />or tree density transects to achieve sampling adequacy. <br />x =sample mean of production per exclosure, percent basal <br />Dover per quadrat or density per transect. <br />s =sample standard deviation <br />z =statistic (z = 1.28 for 90~ ~nfidence level and 0.84 <br />for 808 confidence). <br />d =amount of reduction it is desired to detect (d = 0.1 <br />for 90~ ~nfidence and 0.2 for 80~ confidence). <br />• substitution of the actual sample size for N~ and solving for z <br />~ provides a means for determining the actual confidence limit achieved. <br />Consider a shrubland type with a mean production of 102.8 lbs/acre with <br />a standard deviation of 62.7 lbs/acre for 20 production samples. <br />Determination of Nmin at the 80~ confidence level is provided by: <br />N > 2 (62.7 x 0.84)2 <br />m~ (0.2 x 102.8) 2 <br />N 13 <br />man <br />Using the actual sample size (20) for Nom, the z statistic is determined <br />by: <br />20 (0.2 x 102.8)2 <br />z = 2 <br />62,7 z <br />.- z = 1.04 <br />-18- <br />