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Cover, production and tree density data were evaluated for sampling <br />adequacy using the statistical forrwla: <br />N '2 (s z)2 <br />man (d x) 2 <br />where <br />N~ = minim~nn 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% confidence level and 0.84 <br />for 80% confidence). <br />d = amount of reduction it is desired to detect (d = 0.1 <br />for 90% confidence 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 standazd deviation of 62.7 lbs/acre for 20 production samples. <br />Determination of min at the 80% confidence level is provided by: <br />N > 2 (62.7 x 0.84) 2 <br />m's' (0.2 x 102.8) 2 <br />N = 13 <br />min <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 />