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- ion - <br />/' <br />2 2 <br />' *nmin - t- s <br />(x D)2 <br />where: <br />nmin - a minimum number of observations <br />t = two-tailed test distribution for a given <br />' devel of confidence (80 percent) <br />s = level of accuracy desired for the <br />' _ estimate of the mean (90 percent) <br />x = sample mean <br />' D = desired level of accuracy for a given <br />confidence level <br /> If the results obtained from the equation indicate an <br /> adequate number of samples have not been taken then adds- <br />, tional sampling will be undertaken. Upon completion of the <br /> sampling, a mean and variance will b e calculated and the <br /> Snedecor-Cochren equation will again be used to determine <br />' sample adequacy. This process will be continued until it is <br /> demonstrated that an adequate sample has been taken to supply <br /> a statistically acceptable estimate of the mean and variance <br />' for the characteristic. <br /> Production <br />The next vegetation parameter which requires the collec- <br />lion of quantitative data is herbaceous vegetation production. <br />The randomization process as detailed in the cover section will <br />' also be used in the selection of areas to be sampled for her- <br />baceous vegetation production. However, a single quadrant (50 <br />cm x 20cm or lm x lm) will be established at the starting point <br />of each of the transects and the herbaceous vegetation within <br />the boundaries of the quadrant will be clipped. <br />1 <br />