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III Ill~ll~ll~~ll III Doc Date:12l11/2001 <br />Section 779.119 (b) Continued. Revised 12/3/80 <br />1980 study is presented in Table 28, Summary of Historic and 1980 <br />Vegetation Data. Production data shows a steady decline from 1977 <br />to 1979. Comparisons made with precipitation data disclosed a <br />close correlation between rainfall and production for those years. <br />Cover appeared to remain fairly constant over time. The 1980 data <br />are consistent with the overall average for the types represented. <br />Data from each vegetation type and corresponding reference area <br />were subjected to statistical analysis to determine if there was a <br />significant difference between the sample sites and the chosen <br />reference area (See Table 30, Summary of Statistical Analysis). <br />Comparisons between the sample sites and the reference area were <br />made for cover, production, shrub density, shrub cover based on <br />line intercept, and shrub height. In all cases except one, there <br />was no statistically significant difference at the 90Y confidence <br />level (0,1) between the two. <br />• Table 30, Summary o£ Statistical Analysis, presents statistical <br />information for three separate categories, premine areas, reference <br />areas, and the results of the comparisons made between the premine <br />and reference area data. Under the premine and reference area <br />columns, the sample size (N), average (R), standard deviation (SD) <br />and the sampling precision (con) achieved for each parameter is <br />presented. The third column contains the test statlstic "t" calcu- <br />lated from the premine and reference area data; the critical value <br />of t from a student's t distribution table at the 0.10 level of <br />significance (two tailed test); and the conclusion of the t test <br />reflected by the statements "significant" (S) or "non-significant" <br />(NS) indicating differences between the premine area and reference <br />area means with 90% confidence. <br />Production on the Alkali Sagebrush vegetation type resulted in a <br />significant difference between premine and reference area data. <br />Additional statistical comparisons showed that there was no signi- <br /> <br />779-71 aaa <br />