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Sagebn`ch= 1.662 tt = 2.048 • <br />Since tt > ic, the null hypothesis is accepted and comparability is indicated. <br />Alkali Sagebrush/ Western Wheatgrass <br />tc = 3.158 tt = 2.042 <br />Since it < ic, the null hypothesis is rejected at 95% confidence. At 99.9 <br />confidence, it = 3.646, and k > is indicating comparability at 99.9 % confidence. <br />Mesic Drainace <br />tc = 2.829 tt = 2.069 <br />Since it < Tc, the null hypothesis is rejected at 95% confidence. At 99.9 <br />confidence, Lt = 3.767, and tt > tc indicating comparability at 99.9 % confidence. <br />Thus, comparability of cover data wes indicated for the vegetation types comprising the bulk <br />of the Yoast Baseline and Supplemental areas, and was marginally indicated for the two more <br />minor types. <br />Sample Adequacy <br />1990 Samplinc (Table A22) • <br />Sample adequacy is an estimate of the minimum sample size required to properly represent <br />the variability of a population based on the estimated variance of the population. All of the <br />cover estimates for the six vegetation types sampled in 1990 achieved sample adequacy. <br />Although the 'maximum' sample size of 50 production plots was taken in each, sample <br />adequacy for production estimates was achieved only in the Improved Pasture-Subirrigated <br />type. The Westem Wheatgrass /Alkali Sagebrush vegetation type had the highest cover <br />values of bare soil which greatly influenced the production sample variability; greater bare <br />soil leads to more plots with nil or nearly nil production, increasing sample variance very <br />rapidly. Production values ranged from 3.7 to 134.1 gm/0.5 sq.m. The variability found <br />in the Mesic Drainage vegetation type was probably related to the large variations in the <br />proportion of total cover comprised of herbaceous species, the only part sampled for <br />production. The production levels beneath trees or tall shrubs are often much less than <br />those found in exposed areas, due not only to reduced insolation but also occasionally to <br />trampling or resting of big game and/or livestock. Production values ranged from 26.4 to <br />279.1 gm/0.5 sq.m. Although production samples from the Improved Pasture-Subirrigated <br />were also variable, there was a strong enough central tendency to result in a minimum <br />sample size of 15. • <br />32 <br />