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STA1 E Of ! OI ONnrlO ~+u unni~ ir. r,~w ~~•••••~ <br />DEPARTMENT OF NATURAL RESOURCES <br />D Monte Pascn e, Executive Director <br />l~l 1N EU L.AN U I{ F,(:LAAI A'f10N <br />423 Centennial Building, 1313 Sherman Street <br />Denver, Colorado 80203 Tel. (3031 839-3567 <br />David C. Shelton <br />July 14, 1981 Director <br />TO: Brian Munson <br />FROM: M.S. Savage S QvAG~ <br />RE: Addendum to June 12, 1981 X-G Statistics Memo <br />File No. C-003-80 <br />Brian: <br />rn re-examining the H-G data and my analyses, several additional parameters <br />have been found which meet confidence level (sample adequacy) requirements. <br />They are: <br />1. Reference area Sagebrush community woody plant density. <br />2. Reference area Chokecherry community cover. <br />3. Pre-mine Chokecherry community cover. <br />9. Reference area Aspen community cover. <br />Additionally, the reference area Sagebrush community cover was found to not <br />meet acceptable conficence Levels. <br />There are several parameters For which pre-mine - reference area comparisons <br />can be made. They are Aspen cover, Aspen community tree woody plant density, <br />Chokecherry cover, and Chokecherry woody plant density. <br />The statistical comparison performed was a t-test at 9s% confidence (one-tailed <br />as agreed in the August s, 1980 letter) with the initial hypothesis being that <br />there was no difference between the reference area and pre-mine area. The <br />results are as follows: <br />Aspen cover <br />X pre-mine cover = reference area cover <br />0 <br />N pre-mine cover # reference area cover <br />a <br />t _ 51.7 - 97.3 = 0.822 <br />49.06 99.06 <br />4 + 3 <br />t a(1), v=s,p=.o5 = 2.a15 <br />Conclude that pre-mine cover and reference area cover are equivalent at 9s% <br />confidence (a(I)) . <br />