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2.04.10 Vegetation Information, (continued <br />• Under the previously mentioned guidelines for compliance <br />of vegetation requirements a statistical evaluation was made to <br />determine if the vegetation community was sampled sufficiently <br />to obtain a valid estimate of the means for particluar <br />parameters such as cover, production, and woody plant density. <br />The Snedecor-Cochran sample size adequacy formula. as <br />recommended by the Division, and shown below was used to make the <br />adequacy study. <br />tz s2 <br />Nmin = <br />(~)2 <br />Where: <br />• Nmin the minimum number of observations needed, <br />t = 1.64 (which is the t table value fora double-tailed t <br />test with infinite degrees of freedom at the 90A <br />confidence level), <br />s2 = the sample variance, <br />d = .1 (level of precision for estimate of the mean to be <br />within lOZ of the actual mean), <br />x = sample mean (= the sum of the sample values divided by <br />the total number of samples) <br />The study, as diagrammed in Exhibit H (i), indicates sixteen <br />transacts would have been sufficient for the adequacy study of <br />the cover rather than the eighteen completed. <br />Production of the vegetation cover was determined on May 15, <br />16, then June 15, 16 and the last few days of June and during <br />first few days of July, 1990. Square meter sites were <br />• 3 <br />Rev. 0/04/90 <br />