1987-12-01_PERMIT FILE - C1981017 (247)

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` t WESTERN -- RESOURCE - - - - DEVELOPMENT - r -- CORP. _ P.O.Box 467 -- a 711 Walnut Street*suite 200-. - - - --- • - - -- - -- Boulder, Colorado 80306 (303)449-9009 July -2, 1981 - Mr. Doug Bowman Mid—Continent Resources Box P158 Carbondale, CO 81623 Re: Confidence Levels and Vegetation Type-Acreages -- Dear Doug: Enclosed you will find a table presenting: (1) a calculated t—value,- (2) the corresponding confidence level (two—tailed) for .that t—value,. _ ;.. and (3) a calculated ID—value (the % reduction detectable with 80% confidence) . These figures are given for cover and production means of all affected and corresponding reference areas. One—tailed confi— dence levels are also given 'for production values because we still maintain this is the appropriate statistical procedure. As you can see; there are no problems with -the cover values as they meet all criteria of the'CMLR. This is not true, however, of the production values. None of the confidence limits are within acceptable standards ( two—tailed) although three are acceptable (one—tailed <80%) and two are very close (<75%) . In all cases for these data, confidence levels .should.^be..greater. than or equal Tro-60io while D—values should be less than or equal to 10%.. Our sample sizes are accordingly-.too small for the production data. This is, as you know, the result of an error. - in a published OSM version of the sample adequacy formula and past assurances that we could in fact use a one—tailed t—test (a decision subsequently reversed). The acreages of the affected vegetation types are: Aspen Woodland 83.5 acres, Aspen Shrubland 16.6 acres, Spruce—fir Parkland 36.8 acres, Spruce—fir Forest 4.2 acres, Oak .Shrubland 2.6 acres, and Riparian Woodland 2.0 acres. The total affected acreage is 145.7. II